You still use it as a settlement and security layer. The lightning network is made up of pairs of people that both lock money in a new account with a transaction. Both people get a fully signed copy of a second transaction to reclaim the money, but they don’t publish it immediately. If they need to make a new transaction between each other, they just replace the second fully signed transaction with a new one that divides the money according to the new balance. They can do this as many times as they want for as long as they want, and they only have to make two transactions: one to start and one to stop. If anyone tries to cheat, the only thing they can do is publish an older version of that second transaction that favors them, but you have… I think a day or three, I forget, to publish a newer version that proves they cheated, and if you do, you get ALL the money even if some was owed to them, so cheating won’t go well. The down side is you need a node that’s always online or connects to the network frequently so you can be ready to catch a cheater.

To make a network, they use some fancy cryptography to send money to someone if and only if they send it (minus very, very, very small fees) to the next person in line towards the destination. If anyone in the chain refuses or fails to commit, the transaction fails and no money moves at all. Because it’s all secured by the blockchain, you can trust that everyone both can and will complete the transaction exactly as requested, or the whole thing fails and nothing happens.