Moja majka svako jutro kupuje hleb u prodavnici.

Because moja has to agree with majka.

In Serbian, possessive words like moj / moja / moje change form to match the noun in gender, number, and case.

• majka = feminine singular
• so the correct form is moja

Compare:

• moj otac = my father
• moja majka = my mother
• moje dete = my child

So moja is feminine singular nominative to match majka.

Majka is the subject of the sentence, so it is in the nominative case.

The sentence is about what the mother does:

• Moja majka = the person doing the action
• kupuje = buys

Since she is the subject, Serbian uses the nominative: majka.

Svako jutro means every morning.

Here:

• svako = every
• jutro = morning

Jutro is a neuter noun, so svaki changes to svako to agree with it.

This expression is very common in Serbian as a time phrase. Literally it looks like every morning, and it functions like an adverbial phrase telling when the action happens.

You may also hear svakog jutra, which also means every morning. Both are natural, though svako jutro is especially common and straightforward for learners.

Kupuje is the 3rd person singular present tense form of kupovati.

That matches moja majka = she.

So:

• ja kupujem = I buy / am buying
• ti kupuješ = you buy
• on/ona kupuje = he/she buys

Since majka is she, the verb must be kupuje.

Because this sentence describes a habitual/repeated action: every morning.

In Serbian, aspect matters:

• kupovati = imperfective, used for repeated, ongoing, or habitual buying
• kupiti = perfective, used for a completed single act

So:

• Moja majka svako jutro kupuje hleb... = My mother buys bread every morning.
  → habitual, repeated action

If you said kupi, it would not fit as naturally with the repeated idea svako jutro.

Because hleb is a masculine inanimate noun, and in the singular its accusative form is the same as its nominative form.

Here hleb is the direct object of kupuje, so it is in the accusative case.

But with many masculine inanimate nouns:

• nominative: hleb
• accusative: hleb

So the form does not change, even though the case does.

This is very common in Serbian.

You know from the meaning and the verb relationship.

In Moja majka svako jutro kupuje hleb u prodavnici:

• moja majka = the one doing the action
• kupuje = buys
• hleb = the thing being bought

Even when the noun form does not visibly change, Serbian speakers understand its role from:

• sentence meaning
• verb structure
• context
• word order

So even though hleb looks the same as nominative, it is functioning as the accusative object here.

Because u can take different cases depending on meaning.

• u + locative = in / at a place
• u + accusative = into / to a place, with movement toward it

Here the meaning is location:

• she buys bread in / at the store

So Serbian uses u prodavnici = in the store / at the store.

If the sentence were about going into the store, you would use the accusative:

• Ide u prodavnicu. = She is going to the store.

Because after u expressing location, the noun goes into the locative case.

The base noun is:

• prodavnica = store

Its locative singular form is:

• prodavnici

So:

• u prodavnici = in the store / at the store

This is a regular pattern for many feminine nouns ending in -a.

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

So a noun like hleb can mean:

• bread
• a bread
• the bread

And prodavnici can mean:

• in a store
• in the store

The exact meaning usually comes from context.

That is normal in Serbian, and learners quickly get used to it.

No, Serbian word order is fairly flexible because the case endings help show what each word is doing.

The given order:

• Moja majka svako jutro kupuje hleb u prodavnici.

is a neutral, natural way to say it.

But other orders are also possible for emphasis, for example:

• Svako jutro moja majka kupuje hleb u prodavnici.
• Hleb moja majka svako jutro kupuje u prodavnici.

These versions can sound more marked or emphasize different parts of the sentence.

So the original sentence has a very normal, everyday word order, but it is not the only possible one.