Після тренування я приймаю ванну, а не душ.

Because після is a preposition that requires the genitive case in Ukrainian.

• тренування is the dictionary form: тренування
• In the genitive singular, it is also тренування

So:

• після тренування = after the training / after the workout

This can be confusing because some neuter nouns have the same form in the nominative and genitive singular. Here, the form happens to look unchanged, but the case is still genitive.

Тренування usually means training, a workout, or exercise session, depending on context.

In this sentence, a natural English equivalent is often:

• after training
• after my workout
• after exercising

So it does not have to mean formal athletic training only. It can also refer to going to the gym or doing exercise.

That is a very common question. In Ukrainian, приймати has several meanings, and one of them appears in fixed expressions like:

• приймати ванну = to take a bath
• приймати душ = to take a shower

So here приймаю does not mean I accept. It is part of an idiomatic everyday expression.

A learner may also hear:

• брати ванну
• брати душ

But приймати ванну / душ is standard and very common.

Because ванну is in the accusative case, since it is the direct object of приймаю.

The noun is:

• nominative: ванна = bath
• accusative: ванну

This happens because ванна is a feminine noun ending in -а, and feminine nouns of this type usually change -а to -у in the accusative singular.

So:

• я приймаю ванну = I take a bath

Because душ is a masculine inanimate noun, and for most masculine inanimate nouns, the accusative singular is the same as the nominative singular.

So:

• nominative: душ
• accusative: душ

That is why you get:

• приймаю душ

not приймаю душу

Be careful: душу is actually a different word form from душа meaning soul.

А не is a very common way to express contrast: but not, rather than, or not X but Y.

So:

• я приймаю ванну, а не душ = I take a bath, not a shower

Here а marks a contrast between the two options:

• ванну
• душ

Using а не makes the contrast explicit and natural.

Yes, приймаю is present tense, first person singular: I take / I am taking.

Ukrainian present tense can often correspond to either:

• I take
• I am taking

depending on context.

In this sentence, the most natural interpretation is usually habitual:

• After training, I take a bath, not a shower.

But in the right context, it could also describe what is happening now.

Yes, it can often be omitted.

Ukrainian verbs usually show the person clearly, and приймаю already tells us the subject is I. So both are possible:

• Після тренування я приймаю ванну, а не душ.
• Після тренування приймаю ванну, а не душ.

Including я can make the sentence:

• clearer
• more explicit
• slightly more emphatic

So the version with я is completely normal.

Yes. Ukrainian word order is more flexible than English word order, although not completely free.

The sentence as given is neutral and natural:

• Після тренування я приймаю ванну, а не душ.

But you could also hear variants like:

• Я після тренування приймаю ванну, а не душ.
• Ванну, а не душ, я приймаю після тренування.

Different word orders can shift emphasis. For example, putting ванну, а не душ earlier can emphasize the contrast more strongly.

Still, for learners, the original version is an excellent standard pattern.

It can mean either, depending on context.

Ванна may refer to:

• the bathtub
• the bath as an activity, in expressions like приймати ванну

If you want to say bathroom, the usual word is:

• ванна кімната

or simply

• ванна in informal speech, depending on context

But in приймати ванну, it clearly means to take a bath, not to take a bathroom.

Yes. Приймати душ is a normal expression meaning to take a shower.

So the contrast in the sentence is very natural:

• приймаю ванну = take a bath
• приймаю душ = take a shower

That is why а не душ works smoothly here: the second part leaves out the repeated verb because it is understood.

Full version:

• Після тренування я приймаю ванну, а не приймаю душ.

But Ukrainian, like English, usually avoids repeating what is obvious.