По утрам я иногда подметаю прихожую веником, если с обуви падает песок.

По утрам means in the mornings or morning after morning. It emphasizes a repeated, habitual time.

This is a common Russian pattern:

• по утрам = in the mornings
• по вечерам = in the evenings
• по выходным = on weekends

By contrast, утром usually means in the morning for a specific occasion, though it can sometimes be used more generally too. In this sentence, по утрам is the most natural way to show a routine.

In Russian, the present tense of an imperfective verb is often used for habitual actions, just like English present simple.

So я иногда подметаю means I sometimes sweep as a regular or repeated action, not necessarily right now.

Here, подметаю is imperfective because the sentence describes something that happens from time to time, not one completed action.

Because the sentence is about a repeated habit, not a single completed event.

• подметаю = I sweep / I am in the habit of sweeping / I sometimes sweep
• подмету = I will sweep once, to completion

If you said по утрам я иногда подмету..., it would sound wrong because sometimes in the mornings suggests a repeated pattern, and Russian normally uses the imperfective for that.

Прихожую is the accusative singular form, because it is the direct object of подметаю.

You are sweeping what?
→ прихожую

Base form:

• прихожая = entryway, hallway

In the accusative singular:

• прихожую

So the sentence literally has the structure:

• I sweep the entryway

Because it originally is an adjective in form, and it still declines like one, even though it functions as a noun.

Russian has a number of nouns like this. Прихожая literally comes from an adjective meaning something like entry or front, but in modern Russian it commonly means entryway / hall as a noun.

That is why its forms look adjective-like:

• nominative: прихожая
• accusative: прихожую
• prepositional: в прихожей

So yes, it means a noun here, but it declines like an adjective.

Because веником is instrumental case, which is often used for the tool or means by which something is done.

Here, веник = broom
But with a broom / using a broom = веником

So:

• подметаю веником = I sweep with a broom

This is a very common pattern in Russian:

• писать ручкой = to write with a pen
• резать ножом = to cut with a knife
• есть вилкой = to eat with a fork

It is genitive after с in the sense of from / off.

• обувь = footwear, shoes
• с обуви = off the shoes / from the footwear

So the idea is that sand is falling off the surface of the shoes.

This is different from из обуви, which would mean out of the inside of the shoes. Here the sand is presumably stuck to the outside or underside, so с обуви is the natural choice.

Also note that обувь is usually a singular collective noun in Russian, even though in English we often think in terms of shoes.

Because песок is a mass noun, like sand in English. Russian treats it as singular here.

So:

• падает песок = sand falls / sand is falling

If you wanted to talk about individual grains, you could use a different word such as песчинки:

• падают песчинки = grains of sand are falling

But in this sentence, the general substance sand is what matters, so singular песок is normal.

Because если introduces a subordinate clause.

Main clause:

• По утрам я иногда подметаю прихожую веником

Subordinate clause:

• если с обуви падает песок

Russian normally separates this kind of if clause with a comma, whether it comes before or after the main clause.

For example:

• Я подметаю прихожую, если с обуви падает песок.
• Если с обуви падает песок, я подметаю прихожую.

Both need the comma.

That word order is natural and neutral in Russian:

• По утрам я иногда подметаю...

It means In the mornings, I sometimes sweep...

Russian word order is flexible, so other placements are possible, but they may shift emphasis:

• По утрам иногда я подметаю... = stronger focus on I
• Я по утрам иногда подметаю... = also possible, slightly different rhythm
• Я иногда по утрам подметаю... = also natural

So the position of иногда here is not the only possible one, but it is a very normal one.

Yes, but it would mean something slightly different.

• подметаю прихожую = I sweep the entryway
  This focuses on the room as the object being cleaned.

• подметаю в прихожей = I sweep in the entryway
  This focuses more on the location where the sweeping happens.

In many situations, both are possible, but подметать прихожую is the more direct and natural way to say sweep the hallway/entryway.

Grammatically, обувь is singular in Russian, even though its meaning is collective and often corresponds to English shoes or footwear.

So Russian says:

• с обуви падает песок

not because there is only one shoe, but because обувь is treated as one collective thing.

This is similar to how English uses furniture or clothing as singular mass nouns.