"Ponimaesh" is a slang term in Russian that roughly translates to "do you understand?" or "you got it?" It is commonly used in informal conversations to check if the other person comprehends or agrees with what was said.
"A ty ponimaesh" is a phrase in Russian which means "Do you understand?"
It is not a word in English - gibberish.
This phrase in Russian translates to "Do you understand Russian well?"