Često učim jezik sa sestrom, jer ona uči brže nego ja.

They are two different present-tense forms of the same verb, učiti (to learn / to study / to teach, depending on context).

In this sentence:

• učim = I learn / I study
• uči = she learns / she studies

So:

• ja učim = I am learning / I learn
• ona uči = she is learning / she learns

A few present-tense forms of učiti are:

• ja učim = I learn
• ti učiš = you learn
• on/ona/ono uči = he/she/it learns
• mi učimo = we learn
• vi učite = you (plural/formal) learn
• oni/one/ona uče = they learn

Serbian often drops subject pronouns when they are obvious from the verb ending, but here ona and ja are useful for contrast.

Because the preposition sa / s (with) requires the instrumental case when it means together with someone.

The noun sestra (sister) changes in the instrumental singular:

• sestra = nominative
• sestrom = instrumental

So:

• sa sestrom = with my sister / with a sister depending on context

This is one of the most common uses of the instrumental case in Serbian.

More examples:

• sa prijateljem = with a friend
• sa mamom = with mom
• sa profesorom = with the professor

Sa and s are basically the same preposition here. Both mean with.

• s is the shorter basic form
• sa is often used for easier pronunciation, especially before certain consonants or consonant clusters

With sestrom, Serbian normally uses sa sestrom, because s sestrom would be awkward to pronounce.

So this is mostly a pronunciation-driven choice, not a meaning difference.

Examples:

• s njim = with him
• sa sestrom = with my sister
• sa školom = with the school

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

So jezik can mean:

• a language
• the language
• sometimes simply language

The exact meaning depends on context.

That is very normal in Serbian. For example:

• imam knjigu = I have a/the book
• volim muziku = I like music
• učim jezik = I am learning a/the language

If you want to be more specific, Serbian usually does that with context, adjectives, or demonstratives:

• ovaj jezik = this language
• srpski jezik = the Serbian language / Serbian language

Često means often.

It is an adverb, and Serbian word order is fairly flexible. Putting često near the beginning is very natural:

• Često učim jezik sa sestrom. = I often study the language with my sister.

You could move it for emphasis, though some versions sound more natural than others:

• Često učim jezik sa sestrom. = neutral, very natural
• Jezik često učim sa sestrom. = stronger focus on jezik
• Sa sestrom često učim jezik. = stronger focus on with my sister

So the sentence starts with često simply because that is a common, natural place for frequency adverbs.

Yes. Jer means because, and zato što also means because.

So these are both possible:

• Često učim jezik sa sestrom, jer ona uči brže nego ja.
• Često učim jezik sa sestrom, zato što ona uči brže nego ja.

In many everyday situations, both are fine. Jer is shorter and very common.

A small style note:

• jer is simple and direct
• zato što can sound a bit fuller or more emphatic in some contexts

But for a learner, it is enough to know that both often translate as because.

Brže is the comparative form of the adverb brzo (quickly / fast).

So:

• brzo = quickly, fast
• brže = more quickly, faster

In this sentence, it describes how she learns:

• ona uči brže = she learns faster

This is an adverb, not an adjective.

Compare:

• On je brz. = He is fast. → adjective
• On trči brzo. = He runs fast. → adverb
• On trči brže nego ja. = He runs faster than I do. → comparative adverb

So brže is used because the comparison is about the manner of learning, not about what kind of person she is.

Because the comparison here is really short for a full clause:

• ona uči brže nego ja [učim]

So literally, the idea is:

• She learns faster than I do

Since the hidden subject of the omitted verb is ja, the nominative form ja is used.

This is a very common Serbian pattern after nego in comparisons.

Compare:

• On je viši nego ja. = He is taller than I am.
• Ona radi više nego ja. = She works more than I do.

English often says than me in everyday speech, but Serbian normally uses the form that matches the underlying clause, so nego ja is natural here.

Yes. Serbian often leaves out words that are understood from context.

So:

• nego ja
  is short for:
• nego ja učim

Both communicate the same idea, but the shorter version is more natural in everyday speech.

Full version:

• Često učim jezik sa sestrom, jer ona uči brže nego ja učim.

This is grammatically understandable, but it sounds more repetitive because učim/uči has already appeared. Serbian often avoids repeating what is obvious.

Yes. Jezik can mean both:

• language
• tongue

Like English tongue/language, the exact meaning depends on context.

In this sentence, because of učim (I learn / study), jezik clearly means language.

Examples:

• Učim jezik. = I am learning a language.
• Boli me jezik. = My tongue hurts.

So the word itself has both meanings, but the context makes the intended one clear.

Serbian word order is more flexible than English word order, but not completely free. You can move parts of the sentence to change emphasis.

The original sentence is very natural:

• Često učim jezik sa sestrom, jer ona uči brže nego ja.

Possible variations:

• Jezik često učim sa sestrom, jer ona uči brže nego ja.
• Sa sestrom često učim jezik, jer ona uči brže nego ja.

These are possible, but they may sound more marked or emphasize a different part of the sentence.

The basic point is:

• English usually needs a stricter order
• Serbian allows more movement for focus, topic, and style

For a learner, the original version is a good neutral model.

This sentence contains č in često, and ć in uči(m).

These are different sounds in Serbian, and English speakers often confuse them.

A simple learner-friendly approximation:

• č = a harder ch sound, roughly like ch in church
• ć = a softer sound, somewhere between English t
  • y and a very soft ch, depending on your accent

So:

• često starts with the harder č
• uči / učim contains the softer ć

In careful Serbian pronunciation, the distinction matters, even though many beginners need time to hear and produce it clearly.

Yes, it could.

Because the verb form uči already shows third person singular, Serbian can often omit the pronoun:

• jer ona uči brže nego ja
• jer uči brže nego ja

Both are possible.

Including ona adds clarity and contrast. It slightly emphasizes she:

• because she learns faster than I do

That makes sense here, because the sentence is comparing her and me.

So ona is not strictly necessary, but it is very natural and useful.

It can mean either, depending on context.

In Serbian, učiti covers a range that English often splits into learn and study.

So this sentence could naturally correspond to either:

• I often learn a language with my sister
• I often study a language with my sister

In real context, English would usually choose whichever sounds more natural for the situation.

Related verbs and meanings:

• učiti = learn, study, sometimes teach
• naučiti = learn/master something, come to know it, learn completely

So učiti here suggests an ongoing process, which fits am learning / study very well.