Sestra mi pomaže u kuhinji.

Here mi means to me.

With the verb pomagati (to help), Serbian usually puts the person being helped in the dative case, so:

• pomaže mi = helps me
• literally, something like helps to me

This mi is the short, unstressed form of meni.

• Sestra mi pomaže. = neutral, everyday wording
• Sestra meni pomaže. = more emphatic, as in My sister helps me (maybe not someone else)

Important: in this sentence, mi does not mean my.

Because the subject is sestra (sister), which is third person singular: she.

So the verb pomagati in the present tense becomes:

• ja pomažem = I help
• ti pomažeš = you help
• on/ona pomaže = he/she helps

Since sestra = she, you need pomaže.

Sestra is in the nominative singular, because it is the subject of the sentence — the person doing the action.

So in Sestra mi pomaže u kuhinji:

• sestra = the one who helps
• mi = the person receiving help
• u kuhinji = where the action happens

Serbian often leaves out possessives like moj / moja / moje when talking about close family members, especially if the meaning is already clear from context.

So:

• Sestra mi pomaže u kuhinji. can naturally mean My sister helps me in the kitchen
• Moja sestra mi pomaže u kuhinji. is also correct, but it sounds more explicit

This is very common with words like:

• mama
• tata
• brat
• sestra

Again, the mi here still means me, not my.

Because u can take different cases depending on meaning:

• u + locative = being in a place
• u + accusative = moving into a place

Here the sentence describes where the helping happens, not movement:

• u kuhinji = in the kitchen

Compare:

• Sestra mi pomaže u kuhinji. = My sister helps me in the kitchen.
• Idem u kuhinju. = I am going into the kitchen.

So kuhinji is used because this is a location, not a destination.

Kuhinji is the locative singular of kuhinja.

Base form:

• kuhinja = kitchen

After u meaning in, it changes to the locative:

• u kuhinji = in the kitchen

For many feminine nouns ending in -a, the locative singular ends in -i, so this pattern is very common.

Yes, normally the person being helped goes in the dative.

Examples:

• Pomažem ti. = I help you.
• Pomaže mu. = She helps him.
• Pomažemo im. = We help them.

This can feel unusual to English speakers, because English uses a direct object:

• I help him

But Serbian treats it differently:

• Pomažem mu
• literally closer to I am helping to him

So mi in your sentence is exactly what you should expect after pomaže.

Yes. The short pronoun mi is a clitic, and Serbian clitics usually like to stand in the second position of the sentence or clause.

That is why:

• Sestra mi pomaže u kuhinji. sounds natural

Here the first element is Sestra, and mi comes right after it.

Serbian word order is fairly flexible, so other orders are possible depending on emphasis, for example:

• U kuhinji mi sestra pomaže. = In the kitchen, my sister helps me.

But the clitic mi still tends to stay near the beginning, in that special second-position slot.

Because Serbian has no articles like a or the.

So kuhinja / kuhinji can mean:

• a kitchen
• the kitchen

The exact meaning depends on context.

That means u kuhinji can naturally be translated as in the kitchen here, even though there is no separate word for the.

The form pomaže comes from the verb pomagati, which is the imperfective verb to help.

Serbian often has verb pairs:

• pomagati = imperfective, ongoing/repeated helping
• pomoći = perfective, to help / to give help successfully

In this sentence, pomaže suggests an ongoing or habitual action, such as:

• she is helping me
• she helps me

This is the normal choice for a plain present-tense statement like this one.

Yes. Depending on context, it could be translated as:

• My sister helps me in the kitchen.
• My sister is helping me in the kitchen.
• Sister helps me in the kitchen. (less natural in normal English, but possible in special contexts)

Serbian present tense often covers both:

• a general/habitual meaning
• an action happening now

So the exact English version depends on the situation.