Мазь уже впиталась, поэтому можно снять бинт.

Because the subject is мазь, which is a feminine singular noun.

In the past tense, Russian verbs agree with the subject in gender and number:

• впитался = masculine
• впиталась = feminine
• впиталось = neuter
• впитались = plural

So:

• крем впитался = the cream soaked in
• мазь впиталась = the ointment soaked in

The -сь / -ся part is the reflexive ending of the verb впитаться.

The dictionary form is впитаться.

This is a perfective reflexive verb meaning something like:

• to soak in
• to be absorbed

In this sentence, впиталась means the action is complete: the ointment has already been absorbed.

A related imperfective verb is впитываться, which describes the process:

• Мазь впитывается. = The ointment is soaking in / being absorbed.
• Мазь впиталась. = The ointment has soaked in.

Not literally.

Russian -ся / -сь is often called reflexive, but it does not always mean oneself in the English sense. In many verbs, it changes the verb into something more like an intransitive or state/result verb.

Compare:

• впитать что-то = to absorb something
• впитаться = to be absorbed / to soak in

So мазь впиталась is not really the ointment absorbed itself. It simply means the ointment soaked in.

Уже means already.

It shows that the absorption has happened by now, and this completed state is the reason for the next part of the sentence:

• Мазь уже впиталась = The ointment has already soaked in
• therefore:
• можно снять бинт = the bandage can now be removed

Without уже, the sentence would still be grammatical, but it would lose the idea that this has happened by this point.

Поэтому means:

• therefore
• so
• that’s why
• for that reason

It connects the first clause to the result:

• Мазь уже впиталась, поэтому можно снять бинт.
• The ointment has already soaked in, so the bandage can be removed.

It is very common in Russian for showing cause → result.

Compare:

• потому что = because
• поэтому = therefore / so

For example:

• Можно снять бинт, потому что мазь уже впиталась.
• Мазь уже впиталась, поэтому можно снять бинт.

These are close in meaning, but the structure is different.

Because можно often forms an impersonal construction in Russian.

Можно means:

• it is possible
• one can
• it’s okay to
• you may

So можно снять бинт literally means something like:

• it is possible to remove the bandage
• the bandage can be removed now
• you can remove the bandage now

Russian often leaves the person unspecified when it is obvious or unimportant.

If you want to name the person, you could say:

• Ты можешь снять бинт. = You can remove the bandage.
• Теперь можно снять бинт. = Now the bandage can be removed / now you can remove it.

Because снять is perfective, and here the idea is a single completed action: removing the bandage.

After можно, either aspect may be possible, but the choice changes the meaning:

• можно снять бинт = it is okay / possible to remove the bandage now; one completed act
• можно снимать бинт = it is okay to be removing the bandage / to remove it in general; less natural here

Since the sentence is about the ointment having already soaked in, the natural next step is a completed action, so снять fits best.

Бинт is the direct object of снять, so it is in the accusative case.

But бинт is a masculine inanimate noun, and for masculine inanimate nouns, the accusative singular is usually the same as the nominative singular.

So:

• nominative: бинт
• accusative: бинт

That is why the form does not visibly change.

Compare with an animate noun:

• Я вижу врача. = I see the doctor.

Here the accusative does change.

Here снять means to take off or to remove.

It is used for removing something from a surface, body, hook, wall, etc.

Examples:

• снять пальто = to take off a coat
• снять повязку = to remove a dressing
• снять бинт = to remove a bandage

So in this sentence it means physically taking the bandage off.

They are related, but not identical.

• бинт = a bandage, especially the strip of gauze/material itself
• повязка = a dressing/bandage, often focusing more on what is tied or placed on a wound as a covering

In real usage, both can sometimes fit medical contexts, but бинт specifically refers to the bandage material being wrapped and then removed.

So снять бинт sounds very natural here.

Yes. Russian word order is flexible, though the original sentence is neutral and natural:

• Мазь уже впиталась, поэтому можно снять бинт.

Other possibilities:

• Уже впиталась мазь, поэтому можно снять бинт.
  This is possible, but sounds more marked or stylistic.

• Бинт можно снять, потому что мазь уже впиталась.
  Same basic meaning, but the emphasis begins with the bandage.

Russian word order often changes emphasis rather than basic grammar.

Yes, мазь is a common medical/everyday word.

It usually means:

• ointment
• salve

It refers to a thick medicinal substance applied to the skin.

It is feminine:

• эта мазь
• лечебная мазь

Its soft sign ь does not make it masculine; nouns ending in -ь can be masculine or feminine, and мазь is feminine.

You would usually use an imperfective verb instead of впиталась.

For example:

• Мазь ещё впитывается. = The ointment is still soaking in.
• Мазь не до конца впиталась. = The ointment has not fully soaked in yet.

That would imply that removing the bandage may be premature.

The original sentence uses впиталась because it presents the absorption as completed, which justifies removing the bandage.