Мой друг пьёт воду.

Because друг is a masculine singular noun, and the possessive мой has to agree with it.

• мой = my (masculine singular / neuter singular in some cases)
• моя = my (feminine singular)

So:

• мой друг = my male friend
• моя подруга = my female friend

In this sentence, друг is masculine, so мой is correct.

Here друг is the subject of the sentence, so it stays in the nominative case.

• Мой друг = the person doing the action
• пьёт = drinks / is drinking
• воду = water (the thing being drunk)

If you used друга, that would usually be a different case, often genitive or accusative in other contexts, not the normal subject form.

Because вода is the direct object here, and Russian changes many nouns depending on their role in the sentence.

The dictionary form is:

• вода = water

But after a verb like пить (to drink), the direct object usually goes into the accusative case:

• вода → воду

This is a very common pattern for feminine nouns ending in -а:

• книга → книгу
• машина → машину
• вода → воду

It is the accusative singular form of вода.

Why? Because it is the thing receiving the action:

• My friend drinks what?
• Water

That makes it the direct object, so Russian uses the accusative.

Пьёт is the 3rd person singular form of the verb пить (to drink).

The subject is мой друг = he / my friend, so the verb must match he/she/it form:

• я пью = I drink
• ты пьёшь = you drink
• он / она пьёт = he/she drinks
• мы пьём = we drink
• вы пьёте = you drink
• они пьют = they drink

Since друг is singular, пьёт is the correct form.

It can mean either one, depending on context.

Russian present tense often covers both:

• My friend drinks water
• My friend is drinking water

Without extra context, the sentence could be understood either as a general fact or as something happening now.

It is pronounced roughly like pyot.

A few useful points:

• ь is the soft sign; it softens the consonant before it
• ё is pronounced like yo
• ё is always stressed

So:

• пьёт ≈ pyot

The whole sentence is roughly:

• Мой друг пьёт воду
• moy drook pyot VO-doo

The correct spelling is пьёт with ё.

In many Russian texts, especially informal ones, people often write е instead of ё, so you may see:

• пьет

But it is still understood as пьёт, not пьет with a plain e sound.

For learners, it is best to remember the proper form as пьёт, because ё helps you know both the pronunciation and the stress.

Russian has no articles like English a/an/the.

So Мой друг пьёт воду does not need any extra word for the water or some water.

Russian relies on context instead. Depending on the situation, воду could mean:

• water
• the water
• some water

The exact English translation depends on context, not on a separate article.

No, Russian word order is much more flexible than English word order because the cases help show each word’s role.

The neutral, standard order here is:

• Мой друг пьёт воду.

But other orders are possible, for example:

• Воду пьёт мой друг.
• Пьёт воду мой друг.

These versions can sound more marked, emphatic, or context-dependent. For a beginner, subject + verb + object is the safest default pattern.

Grammatically, yes, you can say:

• Друг пьёт воду.

But it means A friend / the friend is drinking water depending on context, not necessarily my friend.

If you specifically want my friend, you normally keep мой:

• Мой друг пьёт воду.

Russian often omits possessives when ownership is obvious, but in a simple beginner sentence like this, мой is the normal way to express my clearly.

Grammatically, друг is a masculine noun and usually refers to a male friend.

For a female friend, Russian normally uses:

• подруга = female friend

So:

• мой друг = my male friend
• моя подруга = my female friend

In some broader or casual contexts, друзья can mean friends as a mixed group, but the singular друг is masculine.

The stressed syllables are:

• мой
• друг
• пьёт
• во́ду

So the sentence is:

• Мой друг пьёт во́ду.

A useful thing to remember is that ё is always stressed, so in пьёт, the stress must be on ё.