How to say in Czech: How good is her Japanese?

English
How good is
Czech
Jak dobře umí japonsky?
Her Japanese is getting better.
Her Japanese is very good.
Her native language is Japanese.
Is she learning Japanese on her own?
How do you say that in Japanese?
I do not speak Japanese very well.
You speak Japanese very well.
He is Japanese.
He is learning Japanese.
He is not Japanese.

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