A liquidity pool is a smart contract holding two (or more) assets that anyone can trade against: put in one, take out the other, price set by the pool's ratio. Pools replaced order books as the default DEX mechanism because a contract cannot forget to fill you.
Depth is the whole game: a deep pool absorbs size without moving, a thin one turns your market order into the market. That is why routers split trades across pools and chains, hunting the ratio that leaves the most of your value intact.
The U.CASH swap routes across every pool it can reach on 34 networks, scanning depth and splitting routes so the quoted price is the settled price.
Every term behind the rails, the assets, and the settlement.