It is not clear without some context what you are trying to say. It might be, "I would like to do it," or "I am able to do it" or "I would do it if I could," etc. However, your phrase—"I would can do it"—is not correct English in any situation.

The short answer is no: you can't put two modals together like that. The other members have already given proper alternatives.

Конечно, неправильно. Очевидно же, что "I would be able to do it."

I mean I can not use in one phrase two words "would" and "can"

I would be able to do it if I had more time. Is "can" intended to be similar to "able to"?