Если кофемолка шумит слишком громко, я закрываю дверь на кухню.

Russian does not have articles like the or a/an. Whether something is definite or indefinite is usually understood from context.

So:

• кофемолка can mean the coffee grinder or a coffee grinder
• дверь can mean the door or a door

In this sentence, context makes it natural to understand them as the coffee grinder and the door to the kitchen.

Если means if.

Russian often uses the present tense in both parts of a sentence when talking about a general or repeated situation:

• Если кофемолка шумит слишком громко, я закрываю дверь на кухню.

This feels like:

• If the coffee grinder gets too loud, I close the kitchen door
• or Whenever the coffee grinder is too loud, I close the kitchen door

So this is not necessarily one single future event. It sounds more like a usual reaction.

Шумит is from шуметь, which means to make noise, to be noisy, or to make a loud sound.

Here it can be understood as:

• is making too much noise
• is being too loud

Russian often uses verbs like this where English might use an adjective. So instead of saying something like the coffee grinder is too loud, Russian very naturally says the coffee grinder is making noise too loudly / too much.

Because громко is an adverb, and it modifies the verb шумит.

• громкий / громкая / громкое = loud (adjective)
• громко = loudly (adverb)

So:

• громкая кофемолка = a loud coffee grinder
• кофемолка шумит громко = the coffee grinder is making noise loudly / is very loud

In this sentence, the idea is about how it is making noise, so Russian uses the adverb громко.

This is an important difference:

• очень громко = very loudly
• слишком громко = too loudly

Слишком suggests that the loudness has gone beyond what is acceptable or comfortable. So it fits well with the reaction in the second clause: I close the kitchen door.

Закрываю is the imperfective present form of закрывать. Here it suggests a repeated, usual action:

• If it gets too loud, I close the door

If you used закрою, that would be perfective future, and it would sound more like one specific future event:

• Если кофемолка будет шуметь слишком громко, я закрою дверь на кухню.
• If the coffee grinder is too loud, I will close the kitchen door.

So:

• закрываю = habitual / repeated reaction
• закрою = one future action

Most naturally, it describes a habitual or typical situation.

It has the feel of:

• Whenever the coffee grinder is too loud, I close the kitchen door.

That meaning comes from two things:

1. если with present tense
2. закрываю in the imperfective present

So the sentence sounds like something the speaker generally does, not just something happening once.

It is in the accusative case here, because it is the direct object of закрываю.

But for this noun, the accusative singular looks the same as the nominative singular:

• nominative: дверь
• accusative: дверь

This is normal for many inanimate feminine nouns of this type.

So even though the form does not change visibly, the grammatical case is still accusative.

Here на кухню means to the kitchen in the sense of the door leading to the kitchen.

So:

• дверь на кухню = the door to the kitchen

It does not mean that the action закрываю is directed toward the kitchen. Instead, на кухню describes which door is being closed.

In other words, the structure is:

• закрываю [дверь на кухню]
• I close [the door to the kitchen]

Because кухню is accusative, and here the phrase means door to the kitchen or door leading to the kitchen.

Compare:

• на кухню = to the kitchen / leading to the kitchen
• на кухне = in the kitchen

So:

• дверь на кухню = door to the kitchen
• дверь на кухне would mean a door in the kitchen, which is a different idea

This is one of those places where Russian uses a prepositional phrase after a noun to describe destination or direction associated with that noun.

Yes, дверь в кухню is also possible.

Both can mean door to the kitchen, but дверь на кухню is very natural and common in everyday Russian. With nouns like дверь, выход, or окно, Russian often uses в or на depending on the expression and nuance.

So for a learner, the safest thing is to remember дверь на кухню as a normal, idiomatic phrase.

Yes. Russian often omits subject pronouns when the verb ending already makes the subject clear.

So both are fine:

• Если кофемолка шумит слишком громко, я закрываю дверь на кухню.
• Если кофемолка шумит слишком громко, закрываю дверь на кухню.

Including я can add a little emphasis or clarity, but it is not required.

No, Russian word order is fairly flexible.

The given sentence is completely natural:

• Если кофемолка шумит слишком громко, я закрываю дверь на кухню.

But you could also say:

• Я закрываю дверь на кухню, если кофемолка шумит слишком громко.

The basic meaning stays the same. The difference is mostly about emphasis and flow.

The original version is especially natural because it presents the condition first, then the result.