ההרכב מוכן.

Because the noun itself is הרכב (herkev), and Hebrew adds the definite article ה־ to the front:

• הרכב = an ensemble / a lineup / a composition
• ההרכב = the ensemble / the lineup / the composition

So the spelling is literally ה־ + הרכב = ההרכב.

A common pronunciation is:

ha-herKEV muKHAN

A few helpful notes:

• ההרכב = ha-herKEV
• מוכן = muKHAN
• The kh sound is like the ch in Scottish loch or German Bach
• The stress is usually on the last syllable in both words

Yes. הרכב can mean things like:

• composition
• makeup
• lineup
• ensemble

The exact meaning depends on context.

This is also a useful word to distinguish from רכב (rekhev), which means vehicle. Because your sentence has ההרכב with two ה letters, it points to herkev and not rekhev.

In present-tense Hebrew, the verb to be is usually left out.

So:

• ההרכב מוכן = The lineup is ready
• literally: The lineup ready

This is completely normal Hebrew.

But in past and future, Hebrew does use a form of to be:

• ההרכב היה מוכן = The lineup was ready
• ההרכב יהיה מוכן = The lineup will be ready

Because מוכן here is a predicate adjective, not an attributive adjective.

• ההרכב מוכן = The lineup is ready
• ההרכב המוכן = the ready lineup

In other words:

• If the adjective is part of a noun phrase, it usually takes ה too
• If the adjective is the predicate of the sentence, it usually does not

This is a very common Hebrew pattern.

Because מוכן agrees with הרכב, which is masculine singular.

So the adjective is also masculine singular:

• masculine singular: מוכן
• feminine singular: מוכנה
• masculine plural: מוכנים
• feminine plural: מוכנות

For example:

• הקבוצה מוכנה = The group is ready
• ההרכבים מוכנים = The lineups are ready

Yes. מוכן can mean:

• ready
• prepared
• willing

Context decides which meaning is best.

For example:

• אני מוכן can mean I’m ready or I’m willing (said by a male speaker)

In ההרכב מוכן, the natural meaning is usually ready or prepared.

Just add לא before the adjective:

• ההרכב לא מוכן = The lineup is not ready

This is the normal way to negate this kind of sentence in Hebrew.