"Młody lekarz odpoczywa po pracy."

Translation: The young doctor is resting after work.

[Kellstein]

I thought odpoczywa means relaxing as well not just resting

[Jellei]

I personally think it's a little bit of an overinterpretation, but Wiktionary thinks the same as you, so let's say it's close enough.

But as Mateusz said, there's a separate word for "relaxing".

[Krateusz]

Yes, it could be as well but odpoczywać literally means to rest. There's a verb relaksować się, but odpoczywać can be used for both

[gDvA11]

Why not correct: The young doctor is resting after his work.

[Jellei]

Seems correct, added now.