On je prijatelj.

• On = he
• je = is
• prijatelj = friend

So the sentence means He is a friend.

Grammatically, the structure is very close to English:

• subject: on
• verb: je
• noun complement: prijatelj

Serbian does not have articles like a/an or the.

So:

• prijatelj can mean a friend or the friend
• the exact meaning depends on context

In this sentence, English naturally translates it as He is a friend, even though Serbian just says He is friend literally.

Je is the 3rd person singular present-tense form of biti, which means to be.

So:

• ja sam = I am
• ti si = you are
• on/ona/ono je = he/she/it is

In On je prijatelj., je is simply is.

Je is the normal short form used in everyday sentences.

Jeste is the full form, and it is usually used:

• for emphasis
• for contrast
• sometimes in more careful or formal speech

So:

• On je prijatelj. = neutral, normal
• On jeste prijatelj. = He really is a friend / He is a friend indeed

For a basic statement, je is the usual choice.

Yes, Serbian often leaves subject pronouns out when the meaning is already clear from context.

However, there is an important detail: je is a clitic, which means it is an unstressed little word that normally cannot stand at the very beginning of a sentence.

So:

• On je prijatelj. = completely normal
• leaving out on is possible only if the sentence is rearranged or the context makes everything obvious

In beginner sentences, keeping on is the safest and clearest option.

Because it is in the nominative singular masculine form.

After biti (to be), Serbian usually uses the nominative for this kind of sentence:

• On je prijatelj.
• Ona je doktorka.
• To je problem.

Here, prijatelj is not an object. It is a noun that describes or identifies the subject on.

Yes, prijatelj is grammatically masculine and normally refers to a male friend.

The feminine form is:

• prijateljica = female friend

So:

• On je prijatelj. = He is a friend
• Ona je prijateljica. = She is a friend

Yes, Serbian word order is more flexible than English, but not completely free.

The most neutral order here is:

• On je prijatelj.

A very important rule is that je usually comes in the second position in the sentence.

That means:

• On je prijatelj. = normal
• Prijatelj je on. = possible, but marked or emphatic
• On prijatelj je. = not natural

So beginners should treat On je prijatelj. as the standard pattern.

You change both the pronoun and, if needed, the noun.

Examples:

• Ona je prijateljica. = She is a friend
• Oni su prijatelji. = They are friends or They are male/mixed friends
• One su prijateljice. = They are female friends

Notice that:

• je = is
• su = are

A rough English-style guide would be:

ohn yeh pree-YAH-tely

A few useful pronunciation notes:

• j in Serbian sounds like English y
• je sounds roughly like yeh
• lj in prijatelj is a special Serbian sound, somewhat similar to the lli in million for many English speakers, though not exactly the same

So the sentence does not sound like English jay for je. It is closer to yeh.

In Cyrillic, it is:

Он је пријатељ.

Serbian normally uses both scripts:

• Latin: On je prijatelj.
• Cyrillic: Он је пријатељ.

Both are standard Serbian.