Everybody has knowledge about something. If you having basic knowledge it can help you figure out things in your day to day life that you may not know about. Knowledge isn’t always what you learned from school or books, you can attain knowledge from experiences. Knowledge is power only if you know how to use it. If you don’t know how to use it, it’s not going to be any help to you.
The phrase “knowledge is power” means that having knowledgeable can help you out more than physical strength. If you are playing a sport and you are in a game, if you can find your opponents weakness by seeing what they mess up on or what bothers them you can beat their mind.