The Graduate visa lets international students who finish an eligible UK course stay on to work, or look for work, without a sponsor. It does not lead to settlement by itself, so most people use it to find a sponsored job and switch.
Because the Graduate visa cannot be extended, the most common next step is switching to the Skilled Worker visa once you have a sponsored job. Time on the Graduate visa does not count towards settlement, but time on the Skilled Worker route afterwards does.