Transaction batching is a feature or benefit of Account Abstraction. A batch refers to a group of calls that a smart contract account can make inside a single user operation. In order to use batch transactions, a user must have a smart contract account that supports an execute batch function, and they must construct the entire batch before sending the fully constructed (single) user operation to the Bundler.
For example, when you swap in uniswap/1inch using your Metamask, you have to first approve, then wait for the approve to take place, and then swap. In Versa, you can directly batch those transactions atomically, and sign once to execute swapping.