Спочатку я підмітаю кухню, а потім мию підлогу.

Because they are direct objects, so they appear in the accusative case.

• кухня → кухню
• підлога → підлогу

Both nouns are feminine singular, and feminine nouns ending in -а / -я usually change to -у / -ю in the accusative.

So:

• я підмітаю кухню = I sweep the kitchen
• я мию підлогу = I wash the floor

This is one of the most common case patterns in Ukrainian.

In Ukrainian, it is normal to use the room itself as the object of підмітати.

So підмітати кухню literally looks like to sweep the kitchen, but the natural sense is to sweep the kitchen floor / clean the kitchen by sweeping.

English often focuses on the surface, while Ukrainian can focus on the room or area being cleaned.

Compare:

• підмітати кімнату = to sweep the room
• прибирати кухню = to clean the kitchen

So this phrasing is completely natural.

Спочатку means at first, first, or to begin with.

It tells you the first action in a sequence:

• Спочатку я підмітаю кухню... = First I sweep the kitchen...

It is an adverb of time, and it often appears at the beginning of the sentence, though it can be moved for emphasis.

You can say just потім, but а потім is very common and sounds natural when connecting two actions in sequence.

Here:

• а = and / but / while, depending on context
• потім = then / afterwards

In this sentence, а does not mean a strong but. It simply helps link the two steps:

• Спочатку ... , а потім ... = First ..., and then ...

It gives the sentence a nice step-by-step flow.

Both can sometimes translate as and, but they are not identical.

• і simply joins things
• а often joins two parts while also setting them side by side

In sequences like first ..., then ..., Ukrainian very often uses а:

• Спочатку я підмітаю кухню, а потім мию підлогу.

This feels like:

• first one action,
• then the next action.

Using і потім is possible in some contexts, but а потім is especially natural here.

Yes, it can be repeated, but it usually does not need to be.

Ukrainian verbs already show the person clearly:

• підмітаю = I sweep
• мию = I wash

So after я appears once, the second я is often omitted:

• Спочатку я підмітаю кухню, а потім мию підлогу.

You could also say:

• Спочатку я підмітаю кухню, а потім я мию підлогу.

That is grammatical, but slightly more explicit or emphatic. The version without the second я sounds more natural in everyday speech.

They are present tense, first person singular.

• підмітаю = I sweep / I am sweeping
• мию = I wash / I am washing

In Ukrainian, the present tense can cover both:

• a general habit: I sweep
• an action happening now: I am sweeping

So this sentence could describe:

• a routine,
• a set of instructions about what you usually do,
• or what you are doing right now.

Context tells you which meaning is intended.

Because Ukrainian uses the imperfective aspect for:

• repeated or habitual actions
• ongoing processes
• neutral descriptions of what someone does

Here the verbs are:

• підмітати → підмітаю
• мити → мию

These are imperfective.

That fits a sentence like this very well, because it sounds like a routine or a process:

• first I do one thing,
• then I do the next thing.

If you wanted a completed future sense, Ukrainian would usually use perfective verbs instead:

• спочатку я підмету кухню, а потім помию підлогу = first I will sweep the kitchen, then I will wash the floor

So aspect is one reason the sentence sounds like a normal present-time routine.

Their infinitives are:

• підмітати = to sweep
• мити = to wash

The sentence uses the I-form of each verb:

• підмітати → підмітаю
• мити → мию

That -ю ending is a common first-person singular present ending in Ukrainian.

So if you want to recognize the grammar:

• я підмітаю = I sweep
• я мию = I wash

Because Ukrainian has no articles like English a / an / the.

So:

• кухню can mean a kitchen or the kitchen
• підлогу can mean a floor or the floor

The exact meaning comes from context. In this sentence, English naturally uses the kitchen and the floor, but Ukrainian does not need separate words for that.

This is normal across the language.

Yes. Ukrainian word order is fairly flexible, though not completely free.

The original order:

• Спочатку я підмітаю кухню, а потім мию підлогу.

is very natural because it clearly presents the sequence.

You could also hear variations like:

• Я спочатку підмітаю кухню, а потім мию підлогу.
• Кухню я спочатку підмітаю, а потім мию підлогу.

These versions shift the emphasis a little, but the basic meaning stays the same.

So the original sentence is not the only possible order, just the most straightforward one.

Because а connects two clauses:

• Спочатку я підмітаю кухню
• а потім мию підлогу

In Ukrainian, a comma is normally used before conjunctions like а when they join clauses.

So the comma here is standard punctuation, not optional decoration.