That’s correct. Not a native speaker. I am not well versed with slang words. I am sometimes embarrassed because I speak as if they are words from a book instead of sounding like spoken words. Do you know how cuts came to mean that it’s a deal. For a non-native speaker it means the exact opposite thing as in “he cut a wire”. Language evolves in strange ways.
"Cut a deal" is an idiom, not slang: it's appropriate language to use in a business context, for example.
The origin is hazy, of the theories I've seen I consider this the best one: "deal" means both "an agreement" and "to distribute cards in a card game". The dealer, in the latter sense, first cuts the card deck then deals the card. "Cut and deal" -> "cut a deal".
It could also be related to "cut a check", which comes from an era before perforated paper was widespread, when one would literally cut the check out of a book of checks.
