Serverless is a way to run app code without managing the underlying servers yourself. It is like using a shared kitchen: the provider looks after the equipment while you focus on the work you want done.
A small service might run a piece of code only when someone submits a form. The hosting provider handles the machines and can adjust resources as requests change.
Serverless does not mean there are no servers; it means the provider manages them for you. The service still has limits and costs that teams need to understand.