После душа я высушу волосы феном.

Because после requires the genitive case.

The base form is душ (a shower), but after после (after), it changes:

• душ → nominative
• после душа → genitive

So После душа literally means after (the) shower.

This is a very common pattern:

• после работы — after work
• после урока — after the lesson
• после обеда — after lunch

Russian has no articles like a or the.

So после душа can mean:

• after a shower
• after the shower
• after showering

The exact meaning depends on context. In this sentence, English will often naturally say After my shower or After showering, but Russian does not need a separate word for that.

Высушу is a perfective future form. It means the action will be completed: I will dry my hair (fully / successfully).

Compare:

• сушу — I am drying / I dry (imperfective, present)
• буду сушить — I will be drying / I will dry (imperfective future, process-focused)
• высушу — I will dry (perfective future, result-focused)

So this sentence is not just about the process of drying. It is about the completed action after the shower.

They are an aspect pair:

• сушить — imperfective
  Focus on the process, repetition, or general action
• высушить — perfective
  Focus on finishing the action, getting a result

Examples:

• Я сушу волосы. — I’m drying my hair.
• Я высушу волосы. — I’ll dry my hair / I’ll get my hair dry.

The prefix вы- here helps create the perfective verb and gives the sense of bringing the action to completion.

In Russian, when talking about the hair on someone’s head, волосы is normally plural.

So Russian says literally:

• высушу волосы — dry the hairs / dry my hair

This is just the normal idiomatic way to say hair in this context.

Russian also has волос in the singular, but that usually means a single hair.

• У тебя на куртке волос. — There’s a hair on your jacket.
• Я высушу волосы. — I’ll dry my hair.

Because it is in the instrumental case, which is often used to show the tool or means by which something is done.

The noun is:

• фен — a hair dryer

In instrumental singular:

• феном — with a hair dryer / using a hair dryer

So:

• высушу волосы феном = I’ll dry my hair with a hair dryer

This is a very common use of the instrumental case:

• писать ручкой — write with a pen
• резать ножом — cut with a knife
• открыть ключом — open with a key

Not always. Russian often drops subject pronouns when the verb form already makes the subject clear.

Since высушу already means I will dry, you could also say:

• После душа высушу волосы феном.

That sounds natural too.

Including я can help with:

• emphasis
• contrast
• clarity

For example:

• После душа я высушу волосы, а ты уберёшь ванную.
  After the shower, I will dry my hair, and you will clean the bathroom.

So in your sentence, я is correct, but not always required.

Yes, Russian word order is fairly flexible.

This version is neutral and natural:

• После душа я высушу волосы феном.

But you could also say:

• Я высушу волосы феном после душа.
• Волосы я высушу феном после душа.
• Феном я высушу волосы после душа.

The basic meaning stays the same, but the emphasis changes.

Roughly speaking:

• sentence starts with После душа → sets the time/context first
• я → subject
• высушу волосы → main action
• феном → instrument

So the original sentence is a very normal, neutral way to say it.

It can mean either, depending on context.

In everyday Russian, после душа is often used in a broad, natural way to mean:

• after taking a shower
• after the shower
• once I’ve showered

Russian often uses a noun phrase where English might prefer a clause. So instead of saying:

• After I take a shower, ...

Russian can simply say:

• После душа, ...

This is shorter and very idiomatic.

With высушу, it most naturally refers to one future occasion or a specific planned action:

• After the shower, I’ll dry my hair with a hair dryer.

If you wanted to talk about a habitual action, Russian would more naturally use an imperfective verb, for example:

• После душа я сушу волосы феном.
  After a shower, I dry my hair with a hair dryer.

So the perfective высушу points to a single completed future event.

Yes, in everyday Russian фен normally means hair dryer.

So:

• фен — hair dryer
• феном — with a hair dryer

Unlike English, where dryer can refer to several things, Russian фен is specifically the device used to dry hair.

The main stresses are:

• после душа
• я высУшу вОлосы фЕном

More specifically:

• высУшу
• вОлосы
• фЕном

A rough pronunciation guide:

• После душа — POS-lye doo-SHA
• я высушу волосы феном — ya vy-SOO-shu VO-lo-sy FE-nam

A few notes:

• я is pronounced like ya
• unstressed о is often reduced in actual speech
• г does not appear here, so there is nothing unusual to watch for in that respect

Yes, you could, but it is less direct and usually less natural here.

Compare:

• Я высушу волосы феном. — I’ll dry my hair with a hair dryer.
• Я высушу волосы с помощью фена. — I’ll dry my hair with the help of a hair dryer.

The second version is grammatically correct, but it sounds more formal or wordy. In ordinary speech, феном is the normal choice.

Russian often leaves out possessives like my, your, his, etc. when the meaning is obvious from context.

So:

• Я высушу волосы.
  naturally means I’ll dry my hair.

It would usually be unnecessary to say мои волосы here unless you want emphasis or contrast:

• Я высушу мои волосы, а не парик.
  I’ll dry my hair, not the wig.

In normal speech, just волосы is enough.