If an action is being done in order to accomplish something, or for the purpose of accomplishing something, the verb describing what is to be accomplished ends with the Type 9 suffix -meH, which may be translated for, for the purpose of, in order to. The purpose clause always precedes the noun or verb whose purpose it is describing.

ja'chuqmeH rojHom neH jagh la'
The enemy commander wishes a truce (in order) to confer.

The phrase ja'chuqmeH rojHom a truce (in order) to confer is the object of the verb neH he/she wants it; the subject is jaghla' enemy commander. The object is a noun rojHom truce preceeded by the purpose clause ja'chuqmeH for the purpose of conferring or in order to confer. (The verb is made up of ja' tell, -chuq each other; thus, confer is tell each other.)

jagh luHoHmeH jagh lunejtaH
They are searching for the enemy in order to kill him/her.

Here the purpose clause is jagh luHoHmeH in order for them to kill the enemy, which is made up of the object noun jagh enemy preceding the verb luHoHmeH in order for them to kill him/her (lu- they--him/her, HoH kill, -meH for). It describes the purpose of the verb lunejtaH they are searching for him/her (lu- they--him/her, nej seek, search for, -taH continuous). Note that, just as in compound sentences, the object noun jagh enemy occurs before each verb for which it is the object. Thus, somewhat more literally, the sentence may be translated In order to kill the enemy, they are searching for the enemy.

Furthermore, just as in compound sentences, the second of two identical nouns may be replaced by a pronoun or, if the context, is clear, left out altogether.

jagh luHoHmeH ghaH lunejtaH
jagh luHoHmeH lunejtaH
They are searching for the enemy in order to kill him/her.

Some more examples

jIpaSqu'mo' narghpu' qaSuchmeH 'eb.
Because I'm very late, the opportunity to visit you has escaped.
(jI- I, paS be late, -qu' emphatic, -mo' because, narghpu' has escaped, qaSuchmeH 'eb opportunity for me to visit you)

qaSuchmeH jIpaSqu'
In order for me to visit you, I'll be very late.
(qa- I [do something to] you, Such visit, -meH for)

When -meH clauses modify nouns in Klingon
Will Martin - From HolQeD 7.3

When I first met -meH I naturally assumed that it created a clause which would be attached to a verb, like all the other dependent clauses.  Sure, Okrand mentioned something about it modifying nouns as well, but that description was somewhat vague and confusing, so I ignored it.  Just because the tool exists, that doesn't mean it is useful or that I have to use it, right? 

Later, I ran into a problem.  How do I translate: "This idea is difficult for me to explain."  My immediate, mindless answer was QIjmeH Qatlh qechvam.  Meanwhile, that sounds like that in order to progress the purpose of explaining, the idea is somehow intentionally difficult.  It sounds like if the idea were easier, it would be less serving to the mission of explaining. 

That is clearly not what I meant.  That's when it dawned on me what Okrand was doing for us when he allowed -meH clauses to modify nouns.  Now, I can say:

Qatlh qechvam vIQIjmeH Qu'

The purpose clause qechvam vIQIjmeH is modifying the noun Qu'.  The task is difficult.  The purpose of the task is that I explain the idea.  This is very awkward to translate into English, but it has very clear meaning in Klingon.  I tend to think of it as, "The in-order-that-I-explain-this-idea task is difficult."  If I actually translate things to others this way, I get very puzzled looks.  I think this is one of those cases where it makes sense to translate one Klingon sentence into two English sentences, as I did earlier.  "This task is difficult.  The purpose of this task is that I explain the idea."  You might also just mash these together in a very loose, but correct translation: "It is difficult for me to explain this idea." 

It is not really a loose translation.  It is an exact translation.  It disturbs many Klingonists because the grammar of the English translation has nothing to do with the grammar of the Klingon translation.  Beginning Klingonists might even go so far as to grind their way through the rules as they understand them and say qechvam vIQIjmeH Qatlh 'oH.  I can only wince.  Klingon is a language, not a code.  Some elements of it are very alien in nature to English speakers. 

Introducing the word Qu' explains what it is that is difficult.  It is a thing which has a purpose.  Tasks have purpose.  In English, we don't often use the words "task" or "mission" to convey meaning like, "It is difficult to explain this idea."  The meaning is there, but we don't express it explicitly. 

What is difficult, after all?  Well, "it" is difficult.  What do we mean by "it?"  Do we mean "This idea is difficult?"  The idea itself may not really be what we'd call difficult.  Explaining the idea, is difficult.  So what is "explaining the idea?"  It is a task.  It is a mission.  It has a purpose. 

Klingon grammar has a perfect tool for this.  It is almost as if this noun was specially built to carry -meH clauses, much the way the English "it" carries the weight of all those "It is difficult to" or "it is easy to" or "it is important to" expressions. 

Qu'vam ta'lu'meH nuH lugh wIvnISlu'

Amusingly, this can be interpreted two ways that are grammatically different, but semantically identical.  In one case, one must choose the correct in-order-that-the-mission-is-accomplished weapon.  In the second case, one must, in order that the mission is accomplished, choose the correct weapon.  Both of these mean, "The correct weapon must be chosen to accomplish the mission." 

Many times, using -meH clauses to modify nouns is the right weapon.  Choose it well.