I think the others found the answer. FYI, lyrics are often grammatically incorrect. It's nice to be able to understand them, but you wouldn't necessarily want to use them as models for how to speak English.

I believe you might have heard this sentence, "We're gonna keep on dancing". Here, "gonna" is a colloquial contraction for "going to," and "we're" is the contraction for "we are."

No, correctly would be "we're going to keep on dancing", or "we're goin' to keep on dancin'."

What you heard was probably We Gon' Keep On Dancin' which is a line from the song Crazy Kids by Kesha. Gon' is a contraction of Gonna which itself is a contraction of Going To. And in slang speech, We Are Gonna is often shortened to We Gonna (with Are omitted), thus We Gon' Keep On Dancin' is a grammatically valid slang phrase meaning We Are Going To Keep On Dancing which is how it would be said in a formal tone.

The phrase “we goin’ keep on dancing” isn’t grammatically correct in standard English. It’s likely an informal or stylized way of saying “We’re going to keep on dancing.” The missing “are” before “goin’” makes it sound more casual, which is common in song lyrics. While it wouldn’t be correct in formal writing, it works in conversational or artistic contexts.