These two switchboard components are often confused, but they protect against different things and a well-protected home needs both.
A circuit breaker protects your wiring and appliances. If a circuit draws more current than it's rated for, the breaker trips to prevent overheating and fire.
A safety switch, also called an RCD (residual current device), protects people. It constantly monitors current flow and cuts power almost instantly, often in well under a second, if it detects current leaking somewhere it shouldn't, such as through a person.
A circuit breaker won't necessarily trip during an electric shock, the current involved can be far too small to overload wiring but still dangerous to a person. That's exactly the gap a safety switch is designed to close.
Open your switchboard (without touching anything inside) and look for switches labelled "RCD", "safety switch" or with a "test" button. If you can't see one, or you're not sure how many circuits it actually covers, it's worth having a licensed electrician check.