Cashu enhances your privacy. When you initiate a transaction with cashu you are simply telling the mint operator to send that payment for you. So no one knows it came from you. There is a trade-off because when you load your wallet with Bitcoin, you get a cashew token that is stored on your phone until you send it. When you initiate the transaction, the mint takes your tokens burns them and the mint operator sends the Bitcoin to wherever you want it to go. And no one knows that it was you that sent it.

This is the simplified explanation.