senmenjo de kao o aratte, sekken de te mo kirei ni suru.

In 洗面所で, the particle で marks the place where an action happens.

So:

• 洗面所 = washroom / bathroom sink area
• 洗面所で = in the washroom / at the washroom sink

This is different from に, which often marks a destination or location of existence. Here, the sentence is describing an action being performed there, so で is the natural choice.

It is the same particle, but a different function.

In 石けんで, で marks the means / tool / method used to do something.

So:

• 石けんで = with soap / using soap

Japanese で is very common and can mark:

• the place of an action: 洗面所で
• the means or tool: 石けんで

So this sentence uses で twice, but each one is doing a different job.

洗って is the て-form of 洗う.

• 洗う = to wash
• 洗って = washing..., wash and...

In this sentence, the て-form connects actions:

• 顔を洗って、石けんで手もきれいにする。
• Wash your face, and clean your hands with soap too.

The て-form often means:

• and
• and then
• sometimes after doing X

Here it links the first action to the second one in a natural sequence.

In Japanese, when actions are connected, the earlier verb(s) often go into て-form, and the final verb is the one that carries the tense/style.

So here:

• 洗って connects the first action
• する finishes the sentence

This is a very standard pattern:

• Aして、Bする
• do A, and do B

If the whole sentence were polite, the last verb would usually be polite:

• 洗って、石けんで手もきれいにします。

Because も is replacing を here.

Normally, you would expect:

• 手をきれいにする = make the hands clean

But the sentence says:

• 手もきれいにする

The particle も means also / too, and when it is used this way, it often takes the place of another particle such as を.

So:

• 顔を洗って = wash your face
• 手もきれいにする = clean your hands too

The idea is: not only the face, but the hands as well.

きれい is a na-adjective / adjectival noun, and before する it changes to きれいに.

Pattern:

• A を きれいにする = make A clean

So:

• 手をきれいにする = make the hands clean / clean the hands

The に here turns きれい into an adverb-like form so it can describe the result of する.

This pattern is very common:

• 部屋を静かにする = make the room quiet
• 字をきれいに書く = write neatly

Yes, きれい can mean both pretty/beautiful and clean/tidy depending on context.

In this sentence, because we are talking about washing and soap, きれい clearly means:

• clean
• possibly nice and clean

So 手もきれいにする means clean your hands too, not make your hands pretty.

This is a very common word with a range of related meanings:

• visually beautiful
• neat
• tidy
• clean

Context tells you which meaning is intended.

Both are possible, but the nuance is a little different.

• 手も洗う = also wash your hands
• 手もきれいにする = also make your hands clean / clean your hands too

Using きれいにする puts a little more focus on the result: the hands becoming clean. Since 石けんで is included, that fits well.

So the sentence is not just about the washing action itself, but about getting the hands clean with soap.

Yes. Japanese often leaves out the subject when it is obvious from context.

This sentence does not explicitly say who is doing the actions. Depending on the situation, it could mean:

• I wash my face and clean my hands too
• You wash your face and clean your hands too
• One washes one’s face and also cleans one’s hands
• an instruction in a textbook or routine description

Japanese relies heavily on context, so this kind of omission is completely normal.

Yes, it is in the plain style because it ends in する, not します.

That does not automatically mean it is rude. Plain style is commonly used in:

• textbook example sentences
• diary-style writing
• casual conversation
• instructions or descriptions
• captions and notes

A polite version would be:

• 洗面所で顔を洗って、石けんで手もきれいにします。

So the original sentence is best thought of as plain, neutral textbook-style language.

The comma mainly shows a pause and helps readability.

Since 洗って is connecting to the next action, the comma makes the sentence easier to follow:

• 洗面所で顔を洗って、石けんで手もきれいにする。

Japanese commas are often more flexible than English commas. Here it simply marks a natural break between the two linked actions. It does not change the basic grammar.