The following article describes predicates really well: The Power of Predicates: A Purpose-Built Mechanism for Transaction Authorization | by Ryan Sproule | Blockchain Capital Blog | Jan, 2023 | Medium
To quote the article:
“Unlike contract code, predicate code is never “deployed” to the chain. To create a predicate, someone simply writes the code for the predicate and then uses a compiler to generate a code hash, there is no interaction with the chain. Since the hash is both deterministic and collision-resistant, the coins locked in this address can only ever be spent if the predicate conditions are met. To spend a predicate, someone would provide the predicate bytecode (which must match the hash/address that the coins are behind) and a transaction that has the predicate resolve to true.”