اللعبة الجماعية ممتعة.

Because this is a nominal sentence in Arabic. In the present tense, Arabic usually does not use a separate word for is / are.

So:

• اللعبة الجماعية ممتعة literally looks like the group game enjoyable
• but naturally means The team/group game is enjoyable

If you wanted was, will be, etc., Arabic would use other forms, but in the simple present, the copula is usually omitted.

Because in Arabic, adjectives normally come after the noun they describe.

So here:

• اللعبة = the game
• الجماعية = group / collective / team-based

Together, اللعبة الجماعية means the group game or the team game.

This is the opposite of English, where adjectives usually come before the noun.

Because الجماعية is an adjective describing اللعبة, and Arabic adjectives must agree with the noun in definiteness.

Since اللعبة is definite (the game), the adjective must also be definite:

• اللعبة الجماعية = the group game

If the noun were indefinite, the adjective would also be indefinite:

• لعبة جماعية = a group game

This matching is very important in Arabic.

Because ممتعة is not an adjective inside the noun phrase اللعبة الجماعية. It is the predicate of the whole sentence — the part that tells you something about the subject.

So the structure is:

• اللعبة الجماعية = the subject
• ممتعة = the predicate, enjoyable/fun

In Arabic, the predicate in this kind of sentence is often indefinite, so ممتعة does not take الـ.

This difference is important:

• اللعبة الجماعية ممتعة = The group game is enjoyable
• اللعبة الجماعية الممتعة = the enjoyable group game

The second one is just a noun phrase, not a complete sentence.

Because لعبة is a feminine noun in Arabic.

Once the main noun is feminine, words agreeing with it must also be feminine:

• اللعبة = feminine noun
• الجماعية = feminine adjective modifying it
• ممتعة = feminine predicate adjective

This is why they all end with ة here.

Compare with a masculine noun:

• الكتاب ممتع = The book is enjoyable

Here, ممتع is masculine because كتاب is masculine.

It is a nominal sentence made of two main parts:

1. المبتدأ (the topic/subject): اللعبة الجماعية
2. الخبر (the predicate/comment): ممتعة

So the full structure is:

• اللعبة الجماعية = the group game
• ممتعة = is enjoyable

Inside the subject, there is also a smaller noun + adjective combination:

• اللعبة = noun
• الجماعية = adjective describing it

The fully vowelled form is:

اللُّعْبَةُ الجَمَاعِيَّةُ مُمْتِعَةٌ

Those endings show the nominative case, which is expected here because:

• the subject of a nominal sentence is nominative
• the predicate is also nominative

In everyday writing, these short vowels are usually omitted, so you normally see:

اللعبة الجماعية ممتعة

That يّ is part of a very common pattern in Arabic called the nisba adjective, which often means related to or associated with something.

Here the base idea is:

• جماعة = group

From that, Arabic forms:

• جماعيّ = group-related / collective / team-based
• جماعية = the feminine form

Since اللعبة is feminine, the adjective appears as الجماعية.

So this word is basically the feminine adjective meaning group / collective / team-based.

It is pronounced roughly al-luʿ-ba(tu) in careful reading.

The reason you hear a doubled l is that the definite article الـ comes before the letter ل, and that creates a strong l sound.

Also, this word contains ع, which is a consonant that does not exist in English. You do not need a perfect pronunciation at first, but it is good to notice that لعبة is not just luba; the ع is a real consonant in the middle.

The normal, straightforward order is:

اللعبة الجماعية ممتعة

That is the best pattern for a learner.

Arabic can sometimes change the order for emphasis or style, especially in formal or literary contexts, but the basic beginner-friendly structure is:

• subject first
• predicate second

So for now, it is best to keep this order.

It is an adjective, but in this sentence it is being used as the predicate.

So yes, it still means enjoyable / fun, which is adjective-like, but grammatically it is the part that completes the statement about the subject.

You can think of it as:

• adjective in meaning
• predicate in function

That is very common in Arabic.