Quick answer
Как по-ру́сски…?
kak pa-rússki — the shortest version has no verb at all
The options
по-ру́сски, not на ру́сском
Languages as adverbs take по-: по-ру́сски, по-англи́йски, по-неме́цки. These are adverbs, so they never change. На ру́сском языке́ also exists and is more formal — used for books and documents rather than speech.
Chaining the follow-ups
Once you have the word, lock it in: Как э́то пи́шется? (how is it spelled), Где здесь ударе́ние? (where is the stress). Asking about the stress marks you out as a serious learner — and it is the one thing dictionaries on a phone often hide.
What you hear back
Typical mistakes
Как на ру́сском «cheese»?
Как по-ру́сски «cheese»?
Speech uses the по- adverb.
по ру́сски
по-ру́сски
It is written with a hyphen, always.
Check yourself
Which is correct?