Поставьте чашки на поднос, пожалуйста, а я пока накрою стол скатертью.

Поставьте is the imperative form of поставить, meaning put / place / set.

In this sentence it is used either:

• to address more than one person, or
• as the polite singular form, like please put...

So Поставьте чашки... means Put the cups... or Please put the cups...

A native English speaker often notices the ending -ьте. This is very common in polite/plural commands:

• скажите — say / tell
• подождите — wait
• возьмите — take

The less formal singular version would be поставь.

This is a question of aspect.

• поставить is perfective
• ставить is imperfective

In commands, Russian often uses the perfective imperative when the speaker wants a single completed action:

• Поставьте чашки на поднос = Put the cups onto the tray (do it once, complete the action)

If you said ставьте, it could sound more like:

• go ahead and put them
• be putting them
• or a repeated / process-oriented action, depending on context

Here the speaker wants one concrete result, so поставьте is the natural choice.

Чашки is the accusative plural of чашка.

The verb поставить takes a direct object: you put something. So cups must be in the accusative case.

For inanimate plural nouns, the accusative plural is often the same as the nominative plural:

• nominative: чашки
• accusative: чашки

So although the form looks like the dictionary plural, its function here is accusative.

Compare with an animate noun, where accusative plural would usually match the genitive:

• Я вижу студентов — I see the students

Because на can take different cases depending on meaning.

Here there is movement onto a surface, so Russian uses the accusative:

• на поднос = onto the tray

If you were describing location, not movement, you would use the prepositional:

• чашки на подносе = the cups are on the tray

So:

• Поставьте чашки на поднос = put them onto it
• Чашки стоят на подносе = they are standing on it

This movement-vs-location contrast is very important with на and в.

Yes, пожалуйста is flexible.

In this sentence:

• Поставьте чашки на поднос, пожалуйста...

it softens the command and makes it polite: please.

You could also say:

• Пожалуйста, поставьте чашки на поднос
• Поставьте, пожалуйста, чашки на поднос

All are natural. The exact placement changes the rhythm more than the meaning.

English speakers often want one fixed position for please, but Russian is more flexible.

Here а means something like:

• and
• while
• as for me
• meanwhile

It is not exactly the same as simple и.

The phrase а я пока gives a natural contrast of roles:

• You put the cups on the tray, and I’ll meanwhile...

Пока here means for now / meanwhile / in the meantime, not while in the sense of a full subordinate clause.

So the sentence structure is roughly:

• You do this, and meanwhile I’ll do that.

This is a very common conversational use of а:

• Ты готовь овощи, а я сварю рис.
• You prepare the vegetables, and I’ll cook the rice.

Накрою is the 1st person singular future of the perfective verb накрыть.

So it means:

• I will cover
• or in this context, I’ll spread / put on

Because накрыть is perfective, the future is formed with a simple one-word form:

• я накрою
• ты накроешь
• он/она накроет

This is different from imperfective future, which uses быть + infinitive:

• я буду накрывать

Here the speaker means one completed action, so perfective накрою is appropriate.

This follows the pattern:

накрыть что чем

• what is being covered → accusative
• what you cover it with → instrumental

So:

• стол = accusative singular of стол
• скатертью = instrumental singular of скатерть

Literally, this is:

• I’ll cover the table with a tablecloth

This is a very common Russian pattern:

• накрыть диван пледом — cover the sofa with a blanket
• украсить комнату цветами — decorate the room with flowers

English often uses with, while Russian often uses the instrumental case instead of a preposition.

Because it is in the instrumental singular.

The noun скатерть is a feminine noun ending in -ь. In the instrumental singular, nouns of this type often end in -ью:

• скатерть → скатертью
• дверь → дверью
• ночь → ночью

So in накрою стол скатертью, the ending -ью shows the meaning with a tablecloth.

It can mean both, depending on context.

• накрыть стол скатертью clearly means cover the table with a tablecloth
• but накрыть на стол or накрыть стол in many everyday situations can mean set the table / lay the table

For example:

• Пора накрывать на стол. — It’s time to set the table.

In your sentence, because скатертью is explicitly mentioned, the meaning is specifically about putting the tablecloth on the table.

Yes. Russian word order is fairly flexible, though not random.

The sentence:

• Поставьте чашки на поднос, пожалуйста, а я пока накрою стол скатертью.

is natural and neutral.

You could also hear:

• Пожалуйста, поставьте чашки на поднос, а я пока накрою стол скатертью.
• А я пока накрою стол скатертью, поставьте чашки на поднос, пожалуйста.

But changing the order can shift:

• emphasis
• tone
• what sounds more natural in conversation

The original order is very typical because it gives:

1. the request,
2. the politeness marker,
3. the speaker’s parallel action.

Russian has no articles like English a and the.

So:

• чашки can mean cups / the cups
• поднос can mean a tray / the tray
• стол can mean a table / the table
• скатертью can mean with a tablecloth / with the tablecloth

The exact meaning depends on context.

In this sentence, the context probably makes them specific:

• the cups
• the tray
• the table
• the tablecloth

English speakers often want a one-to-one equivalent, but Russian leaves this information to context rather than using articles.