حارس المرمى جاهز.

Because Arabic often uses a nominal sentence in the present tense. In sentences like this, Arabic normally does not use a present-tense verb meaning is/are.

So:

• حارس المرمى جاهز = The goalkeeper is ready

The idea of is is understood automatically.

If you wanted the past tense, Arabic would usually use كان:

• كان حارس المرمى جاهزًا = The goalkeeper was ready

It is a nominal sentence made of two main parts:

• حارس المرمى = the subject
• جاهز = the predicate

More specifically:

• حارس المرمى is a noun phrase meaning the goalkeeper
• جاهز is an adjective in form, but here it functions as the predicate: ready

So the structure is:

• subject + predicate

This is because حارس المرمى is an iḍāfa construction, often called a construct phrase.

In an iḍāfa:

• the first noun is possessed or specified by the second
• the first noun usually does not take الـ
• the whole phrase can still be definite if the second noun is definite

Here:

• حارس = guard / keeper
• المرمى = the goal

Together:

• حارس المرمى = keeper of the goal = the goalkeeper

Because المرمى is definite, the whole phrase is definite.

In an iḍāfa, the first noun normally does not take الـ.

So you get:

• حارس المرمى not الحارس المرمى

This is one of the main signals that you are looking at an iḍāfa phrase.

The definiteness comes from the second noun:

• مرمى = a goal
• المرمى = the goal

So:

• حارس مرمى = a goalkeeper / keeper of a goal
• حارس المرمى = the goalkeeper / keeper of the goal

المرمى literally means the goal or the target. In sports context, it means the goal in football/soccer.

So:

• حارس المرمى literally = guardian/keeper of the goal
• natural English equivalent = goalkeeper

Because it matches حارس المرمى, whose head noun is حارس, a singular masculine noun.

In Arabic, predicates like this usually agree with the subject in gender and number.

So:

• masculine singular: جاهز
• feminine singular: جاهزة
• masculine plural: جاهزون or جاهزين depending on case/style
• feminine plural: جاهزات

Since حارس is masculine singular, جاهز is the correct form.

In fully vocalized formal Arabic, yes, case endings are possible.

A fully inflected version would often be:

• حارسُ المرمى جاهزٌ

Here:

• حارسُ has ḍamma because it is the subject
• جاهزٌ has ḍamma because it is the predicate of a nominal sentence

But in normal everyday writing, short vowels and case endings are usually omitted, so you simply see:

• حارس المرمى جاهز

That is completely normal.

A careful pronunciation is roughly:

• ḥāris al-marmā jāhiz

A few pronunciation notes:

• ح in حارس is a deeper, breathier sound than English h
• ر is usually rolled or tapped
• ى at the end of المرمى sounds like a long ā
• ج in Modern Standard Arabic is usually pronounced like j in judge
• ز in جاهز is like z

If you are learning MSA pronunciation, a useful rough guide is:

• ḥaa-ris al-mar-maa jaa-hiz

The final ى is called alif maqṣūra. It represents a long ā sound at the end of a word, even though it looks different from regular ا.

So in المرمى, the ending is pronounced like -mā.

This spelling is common in many Arabic words, and you simply learn it as part of the word’s written form.

Yes, that would be understandable: حارس الهدف literally means keeper of the goal/target.

However, حارس المرمى is the standard and more natural expression for goalkeeper in sports Arabic.

So for football/soccer context, حارس المرمى is the better choice.

Yes, but the meaning changes slightly.

• الحارس جاهز = The guard / the keeper is ready
• حارس المرمى جاهز = The goalkeeper is ready

So الحارس جاهز is less specific unless the context already makes it clear that you mean the goalkeeper.

It is basically an adjective meaning ready, but in this sentence it works as the predicate.

This is very common in Arabic:

• الولد طويل = The boy is tall
• البيت كبير = The house is big
• حارس المرمى جاهز = The goalkeeper is ready

So جاهز is an adjective in form, but syntactically it is the second main part of the sentence, telling you something about the subject.