Мы нарезали рулет и подали его к чаю.

Because рулет is a masculine inanimate noun in the singular. In Russian, the accusative singular of masculine inanimate nouns looks the same as the nominative singular.

So:

• nominative: рулет
• accusative: рулет

Even though it means a roll / roulade as the direct object, the form does not change.

Рулет usually means some kind of rolled food. Depending on context, it can be:

• a Swiss roll / jelly roll
• a meat roll
• another rolled dish or dessert

So the exact English word depends on what kind of food is being discussed. The Russian word itself focuses on the idea of something rolled up.

Его means it / him, and here it means it, referring back to рулет.

In this sentence, его is the direct object of подали, so it is in the accusative case.

Why does it look like его and not something else?

• masculine singular pronoun, accusative: его
• it refers to рулет, which is masculine singular

So подали его = served it.

A learner may also notice that его can have more than one job in Russian. The same form can be accusative or genitive depending on context. Here it is accusative because it is the thing being served.

Russian often uses a pronoun like English does:

• We sliced the roll and served it with tea.

Using его avoids repeating рулет and sounds natural.

You could repeat the noun, but it would usually sound less smooth unless you wanted special emphasis.

Also, in context, Russian can sometimes omit the object entirely if it is obvious, but его makes the sentence clearer and more explicit.

К чаю literally means something like for tea or with tea in the sense of served as an accompaniment to tea.

The preposition к normally takes the dative case, so:

• чай = nominative
• чаю = dative

So:

• к чаю = for tea / to go with tea

This is a very common Russian expression for food that is served as part of tea drinking.

Not exactly.

• к чаю means for tea, as something served with tea, or to go with tea
• с чаем means with tea more literally, as in together with tea

So подали его к чаю suggests it was served as a tea-time food. If you said с чаем, the focus would be more on the fact that tea was also there.

Both can sometimes be translated as with tea, but the nuance is different.

Нарезали suggests cutting something into slices or pieces, not just cutting in a general sense.

Compare:

• резали = were cutting / cut
• нарезали = sliced up / cut into portions

So with food, нарезали is very natural because it implies preparing it in serving pieces.

It also fits the idea of a completed action in this sentence: first they sliced it, then they served it.

Because подали presents the action as completed: they served it, and that action is done.

This is the normal choice when describing a single completed event in a sequence:

• Мы нарезали рулет и подали его к чаю.

By contrast, подавали would usually suggest:

• a repeated action
• an ongoing/background action
• habitual serving

So подали is the natural form for a one-time completed event.

Because they are in the past tense plural.

In Russian past tense:

• singular masculine often ends in -л
• singular feminine in -ла
• singular neuter in -ло
• plural in -ли

So:

• нарезали = (they/we/you plural) sliced
• подали = (they/we/you plural) served

The ending -ли shows that the subject is plural.

It could be left out if the context already makes the subject clear, but here мы helps identify who did the actions.

That is especially useful because past tense plural forms like нарезали and подали do not tell you the person by themselves. They could mean:

• we
• you (plural)
• they

So мы removes ambiguity.

Because Russian past tense is formed differently from English. Russian does not use an auxiliary like did or have here.

Instead, the verb itself carries the past meaning:

• нарезали = sliced / cut up
• подали = served

So Russian past tense is usually just one word, not an auxiliary plus a main verb.

Yes. Russian word order is more flexible than English, because case endings help show the grammatical roles.

The given sentence has a neutral, natural order:

• Мы нарезали рулет и подали его к чаю.

But other orders are possible for emphasis, for example:

• Рулет мы нарезали и подали его к чаю.
  Emphasis on рулет

• К чаю мы подали рулет.
  Emphasis on к чаю

The basic meaning stays the same, but the focus or style changes.