It's basically a vending machine. You send the mint Bitcoin, they give you ecash tokens.

Trading those tokens around is anonymous. There is no blockchain so the public can't see anything. There are no accounts so the mint doesn't know where the tokens came from. It can only know that the tokens are valid or not. Think of it like cash.

You can send and receive lightning payments, but you aren't directly interacting with the Lightning Network. The ecash mint is doing it on your behalf. But the user experience feels like you are doing it.

Remember that It's custodial (possible for a mint to rug it's users). Also the transaction level privacy is strong, but you still have to protect your network level privacy by using a VPN or Tor to hide your IP address from the mint.

Try it out: https://www.minibits.cash/ or https://wallet.cashu.me/