Planinarenje je zabavno.

Because planinarenje is a neuter singular noun, and the adjective zabavno agrees with it.

In Serbian, predicate adjectives after je usually match the noun in gender and number:

• zabavan = masculine singular
• zabavna = feminine singular
• zabavno = neuter singular
• zabavni / zabavne = plural forms, depending on context

So:

• Film je zabavan. = The film is fun.
• Igra je zabavna. = The game is fun.
• Planinarenje je zabavno. = Hiking is fun.

It is a noun, even though it refers to an activity.

Planinarenje means hiking / mountaineering / the activity of going in the mountains. It is formed like many Serbian activity nouns in -nje or -anje, which often correspond to English -ing forms.

So in this sentence, planinarenje behaves grammatically like a noun, not like a verb.

Je is the 3rd person singular present tense of biti = to be.

So the structure is:

• Planinarenje = subject
• je = is
• zabavno = fun

This is very similar to English Hiking is fun.

In Serbian, this linking verb is normally used in sentences like this.

It is singular.

Even though it describes an activity in a general sense, grammatically it is treated as one neuter noun. That is why the verb is je and not su, and why the adjective is zabavno in the singular neuter form.

It is in the nominative case, because it is the subject of the sentence.

In Planinarenje je zabavno, the sentence is basically:

• planinarenje = what is being talked about
• je zabavno = what is being said about it

The adjective zabavno is also in the nominative-style predicate form, agreeing with the subject.

Yes, in many contexts hiking is a very good translation.

Depending on context, it can also suggest mountain hiking or mountaineering, since it comes from planina = mountain.

So Planinarenje je zabavno can naturally be understood as:

• Hiking is fun
• Mountain hiking is fun
• sometimes Mountaineering is fun, depending on context

A simple English-friendly approximation is:

pla-ni-na-RE-nye

The important part is nj, which is a single Serbian sound, like the ny sound in canyon.

So -nje is not pronounced like separate n + j in English. It is a soft sound:

• nje ≈ nye

And zabavno is approximately:

za-BAV-no

Serbian spelling is very regular, so words are usually pronounced the way they are written.

Because Serbian does not use articles like English the and a/an.

So Planinarenje je zabavno does not need anything equivalent to the hiking or a hiking.

Serbian usually expresses definiteness from context rather than with articles.

Yes, Serbian word order is more flexible than English.

The neutral, standard order here is:

• Planinarenje je zabavno.

But you may also hear:

• Zabavno je planinarenje.

That version can sound more emphatic or stylistically marked, as if highlighting fun first.

Still, for learners, Planinarenje je zabavno is the safest and most neutral version.

No, that would be incorrect.

Zabavan is the masculine singular form, but planinarenje is neuter singular, so you need zabavno.

Agreement is very important in Serbian. The adjective must match the noun:

• masculine: zabavan
• feminine: zabavna
• neuter: zabavno

Yes. Planina means mountain, and planinarenje is the noun for the activity connected with going in the mountains.

This is useful because Serbian learners often recognize word families:

• planina = mountain
• planinar = hiker / mountaineer
• planinariti = to hike / do mountaineering
• planinarenje = hiking / mountaineering

Seeing those connections can make vocabulary easier to remember.

Usually yes in simple sentences like this.

But depending on context, zabavno can also mean:

• entertaining
• enjoyable
• amusing

In Planinarenje je zabavno, fun is the most natural English choice.

Yes, it is completely natural.

It is a simple, standard Serbian sentence with:

• a neuter singular noun for an activity
• the present tense of to be
• a matching adjective

It sounds like a normal general statement, just like Reading is useful or Swimming is healthy in English.