Он заказал виски.

Заказать is the infinitive, meaning to order.
Заказал is the past-tense form: ordered.

In this sentence, the verb is in the past tense masculine singular because the subject is он.

A few matching forms:

• он заказал = he ordered
• она заказала = she ordered
• они заказали = they ordered

So Он заказал виски uses the correct finite verb form for he.

It tells us three things at once:

• past tense
• singular
• masculine

Russian past-tense verbs agree with the subject in gender and number.
Because the subject is он, the masculine past form заказал is used.

Russian does not have articles like a, an, or the.

So виски can mean:

• a whisky
• the whisky
• some whisky

The exact meaning depends on context. In a restaurant or bar, Он заказал виски will often be understood as He ordered a whisky or He ordered whisky.

Виски is a borrowed noun that is usually treated as indeclinable, meaning its form often stays the same across cases.

Here it is the direct object of заказал, so logically it is in the accusative case. But the visible form is still виски.

So:

• dictionary form: виски
• object form here: виски

No ending change appears.

It only looks plural to an English speaker learning Russian because it ends in -и.

In this sentence, виски is the borrowed noun meaning whisky. It is not a normal Russian plural form here. It can refer to:

• the drink in general
• one serving of whisky, depending on context

So you should learn виски as a fixed noun form, not as a regular plural ending.

It is the accusative case, because it is the direct object of the verb заказал.

He ordered what?
→ виски

That said, the form does not visibly change because виски is indeclinable.

Заказал comes from the perfective verb заказать.

Perfective aspect presents the action as a completed whole: he placed the order.

So Он заказал виски sounds like:

• he ordered it
• the ordering happened as a finished event

If you used the imperfective заказывал, the meaning would shift more toward:

• he was ordering
• he used to order
• he ordered repeatedly
• or the action is being described without focusing on completion

So aspect is one reason заказал is very natural here.

Yes, sometimes.

Russian often drops the subject pronoun when the subject is already clear from context. So in the right situation, you could simply say:

• Заказал виски.

However, он is included when you want to:

• make the subject explicit
• contrast him with someone else
• make the sentence clearer on its own

So Он заказал виски is a neutral, complete sentence.

This is the most neutral word order for this sentence:

• Он = subject
• заказал = verb
• виски = object

Russian word order is more flexible than English, so other orders are possible, but they change the emphasis.

For example:

• Он заказал виски. = neutral statement
• Виски он заказал. = emphasis on whisky
• Заказал он виски. = emphasis can fall on the fact that he ordered it, depending on context and intonation

So the original sentence is the plain, unmarked version.

It is pronounced ви́ски, with the stress on the first syllable:

• ВИ-ski

And the whole sentence is:

• Он заказа́л ви́ски.

The verb stress is on the last syllable:

• за-ка-ЗАЛ

In modern Russian, виски is usually treated as masculine and indeclinable.

You can see that more clearly when adjectives are used:

• хороший виски = good whisky

In your sentence, the noun itself does not show gender visibly, because виски does not change form here. So this is something you mainly notice in agreement words like adjectives.