Anneanne, istersen sana bir bardak su getireyim.

Anneanne means maternal grandmother — literally, your mother’s mother.

Turkish often distinguishes:

• anneanne = maternal grandmother
• babaanne = paternal grandmother

A more general word is büyükanne, which means grandmother without specifying which side of the family.

The comma shows direct address, also called the vocative.

So here, Anneanne, ... means the speaker is talking to Grandma.

In English, it works the same way:

• Grandma, do you want...
• John, come here.

İstersen means if you want or if you’d like.

It is built from:

• iste- = to want
• -r = aorist/general tense marker
• -se = conditional, meaning if
• -n = you singular

So the structure is roughly:

iste-r-se-n → if you want

This is a very common Turkish pattern.

In Turkish, if is often built directly into the verb with the conditional suffix -se / -sa.

So instead of saying something like if you want with a separate if, Turkish often says it in one word:

• istersen = if you want
• gelirse = if he/she comes
• vaktin varsa = if you have time

So this is normal Turkish grammar, not a special exception.

Yes, istersen and sana are the singular/informal forms based on sen.

But in Turkish, family members usually use sen with each other, even with elders. That is not automatically rude. With close family, it is often the most natural choice.

A more formal/polite version would be:

• Anneanne, isterseniz size bir bardak su getireyim.

That uses:

• isterseniz = if you want, formal/plural
• size = to you, formal/plural

Sana is the dative form of sen.

• sen = you
• sana = to you / for you

In this sentence, the speaker is bringing something to Grandma, so the dative is needed.

Compare:

• Sen geldin. = You came.
• Sana su getireyim. = Let me bring water to you.

Literally, it is one glass water, but naturally it means a glass of water.

Turkish does not use a separate word like English of in this kind of expression. Measure expressions are usually formed like this:

• bir bardak su = a glass of water
• bir fincan kahve = a cup of coffee
• bir dilim ekmek = a slice of bread

So English of often has no direct equivalent here.

It can mean either, depending on context.

Here, bir bardak su usually means a glass of water, not necessarily emphasizing the number one.

Turkish does not have articles like a or the, so bir often does the job of English a/an.

So:

• bir bardak su = a glass of water
• but in another context it could also emphasize one glass of water

Because it is an indefinite, nonspecific direct object.

In Turkish, direct objects often stay unmarked if they are indefinite or not specific:

• Su getireyim. = Let me bring water.
• Bir bardak su getireyim. = Let me bring a glass of water.

Turkish usually adds the accusative ending only when the object is specific/definite.

So the lack of an accusative ending here is completely normal.

Getireyim means something like:

• let me bring
• I’ll bring
• shall I bring

It comes from getir- = bring.

Then Turkish adds an optative / volitional form for first person singular:

• getir-
• getir-e-yim → getireyim

This form is often used when offering to do something:

• Açayım mı? = Shall I open it?
• Yardım edeyim. = Let me help.
• Su getireyim. = Let me bring water.

So getireyim is not just a plain future; it carries the sense of an offer or willingness.

Because getireyim sounds like an offer.

• getireyim = let me bring / shall I bring / I can bring
• getireceğim = I will bring

In this sentence, the speaker is politely offering something, so getireyim is the natural choice.

If you said getireceğim, it would sound more like a simple statement of future intention, not as much like a polite offer.

Turkish often leaves subject pronouns out because the verb endings already show who the subject is.

Here:

• isterse-n = you want
• getireyim = let me / I should bring

So Turkish does not need to say ben or sen unless there is extra emphasis.

That is why:

• sana is included, because it means to you
• but the subject pronouns themselves are not necessary

The order is very natural for Turkish:

• Anneanne = direct address
• istersen = if you want
• sana = to you
• bir bardak su = a glass of water
• getireyim = let me bring

So the overall structure is:

Grandma, if you want, let me bring you a glass of water.

Turkish word order is fairly flexible, but the verb usually comes at the end. Moving words around can change emphasis, but this version sounds neutral and natural.