I'm still getting my head around it as well but from what I have so far it's essentially a federated sidechain that batches transactions to take them off the base layer. Sort of like Liquid being trust-minimized but the big difference is you don't have to trust the majority of validators like with Liquid. As long as a single validator remains honest the others can't confiscate or freeze pegged-in funds. Again, I could be missing something or mis-understanding as it's fairly new to me as well.