Translation:Can I practise Chinese with you?
In polite English, "can I" is asking if I have the ability. "May I" is seeking permission. So "May I practice Chinese with you?" is more correct.
"Can I" is not less correct. It's informal and very common. 可以 is also widely used in Chinese, and the translation is perfectly fine. "May I" should be an acceptable alternative.
"practise" is the British spelling. I am American, but i favor "practise" because it is more fonetic. I am a firm supporter of (ov) English spelling reform; "foneticizing" as i call it; given that millions of English-speakers ar functionally illiterate, no-one (-wun) should be able to, in good conscience, choose the clearly-less-fonetic ov two or more accepted spellings.
"May I" is the better answer, and at least should be considered interchangeable.
Although "can" is frequently used colloquially in America in this type of sentence, the correct grammar is really "may". Can = do I have the ability, may = polite form for asking permission.