Ray Dex exchange is where you can trade one token for another. It is a simple swap interface, just select the two tokens you wish to exchange.
The liquidity provided to Ray Dex comes from Liquidity Providers ("Ray LPs") who stake their tokens in "Pools". In exchange, they get LP (Liquidity Provider) tokens, which can also be staked to earn Ray Dex tokens in the "farm".
When you make a token swap (trade) on the exchange you will pay a 0.2% trading fee.