The fiat on-ramp refers to the process of exchanging cryptocurrencies from fiat money. These exchanges facilitate fiat-crypto transactions based on the current market value. The sole purpose these processes are termed as on-ramps is that users can get whole access to the crypto market.
Similarly, there are also cryptocurrency off-ramps where users can exchange their crypto assets in exchange for fiat currency based on the current market value. Products or services can also be availed against cryptocurrency. Overall, the idea of fiat on-ramp makes the entire process of entering into the crypto market extremely seamless.