Društvo ima zabavan predlog i dobru ideju.

Društvo can mean several things depending on context: society, company, association, group, or even circle of friends. In this sentence, it most naturally means something like the group or the organization/company.

It is a neuter singular noun.

Ima is the 3rd person singular form of the verb imati = to have.

So:

• ja imam = I have
• ti imaš = you have
• on/ona/ono ima = he/she/it has

Since društvo is grammatically singular, the verb must also be singular: društvo ima = the group has.

Because the two nouns have different gender and one of them shows a different case ending more clearly.

• predlog is masculine singular
• ideja is feminine singular

The adjectives must agree with the nouns in gender, number, and case.

So:

• zabavan predlog = masculine singular
• dobru ideju = feminine singular accusative

That is why the adjective endings are different.

Because ideja is the direct object of the verb ima, so it goes into the accusative case.

For many feminine nouns ending in -a, the accusative singular changes:

• nominative: ideja
• accusative: ideju

So:

• dobra ideja = a good idea (subject form / dictionary form)
• imam dobru ideju = I have a good idea (object form)

For the same reason: the adjective must match the noun it describes.

Since ideju is feminine singular accusative, the adjective also becomes feminine singular accusative:

• nominative: dobra ideja
• accusative: dobru ideju

So the adjective changes together with the noun.

It actually is in the accusative, but for many inanimate masculine singular nouns, the accusative looks the same as the nominative.

So:

• nominative: predlog
• accusative: predlog

The adjective also matches that pattern:

• nominative: zabavan predlog
• accusative: zabavan predlog

So the form does not visibly change, even though the grammatical case is accusative.

Both are in the accusative singular, because they are the direct objects of ima.

The sentence contains two objects connected by i (and):

• zabavan predlog
• dobru ideju

So the full structure is basically:

Društvo (subject)
ima (verb)
zabavan predlog i dobru ideju (two direct objects)

Yes, predlog can mean both:

• proposal / suggestion
• preposition (in grammar)

The meaning depends on context.

In this sentence, because of zabavan and dobru ideju, it clearly means proposal or suggestion, not the grammar term.

Yes, Serbian word order is more flexible than English word order.

The neutral order here is:

Društvo ima zabavan predlog i dobru ideju.

But you could also move things around for emphasis, for example:

• Zabavan predlog i dobru ideju ima društvo.
• Društvo dobru ideju i zabavan predlog ima.

These are less neutral and would sound more marked or stylistic. For learners, the original order is the best and most natural one to use.

Yes. In this sentence, i is the simple conjunction and.

It joins two noun phrases:

• zabavan predlog
• dobru ideju

It does not change the case. Both parts stay in the accusative because both are objects of ima.

A rough pronunciation guide for an English speaker would be:

DROO-shtvo EE-mah ZAH-bah-vahn PRED-log ee DOH-broo ee-DAY-yoo

A few useful sounds:

• š = sh in shoe
• ž = s in measure
• j = English y in yes
• r is rolled or tapped more than in English

So:

• Društvo ≈ DROO-shtvo
• ideju ≈ ee-DAY-yoo

The dictionary forms are:

• društvo = society, company, group
• imati = to have
• zabavan = fun, amusing
• predlog = proposal, suggestion; also preposition
• dobar = good
• ideja = idea

In the sentence, dobar appears as dobru because it agrees with ideju in the accusative.

Yes, absolutely. That simply changes the order of the two objects:

• Društvo ima zabavan predlog i dobru ideju.
• Društvo ima dobru ideju i zabavan predlog.

Both are grammatical. The difference is mostly about emphasis or what you mention first.