On-Ramp is the conversion from fiat to crypto, usually paid by card or bank transfer, and you receive crypto in your crypto wallet. It means using fiat (like USD, EUR, etc.) to buy crypto with card, Apple Pay, Goople Pay or other supported local APMs.
Off-Ramp is the conversion from crypto to fiat, where you send crypto and receive funds in your bank account or card.It means selling your crypto and receiving fiat into your bank account or card.