Science itself literally comes from an old Greek word meaning knowledge. It refers to how humans, since ancient times, have studied the world around them, observed things, and grown to understand how things work, through mathematics, physics, chemistry etc.
It has changed over centuries between focuses and breadth, but it all basically comes back to one thing: the application of what we call the scientific method. Simply put, this is when you make an observation, form a theory, test the theory, and see if your theory holds up. This can relate to complicated experiments, but also day to day life. You don’t need to be a scientist to apply the scientific method!