Yes, rollups are part of a layer 2 solution, so most of the transaction happens off the main chain. It's only the final state that has to be updated to it, so you can tend to pay less in gas prices. All of the smart contract code handling can happen there, instead of on the main chain.

You'll still have to pay for the network fees on the side chain, but they are generally significantly cheaper than on the Ethereum mainnet, and of course the gas when the final state change transaction hits the main blockchain.