How To Work Steem Power?

I'm new here.
I have heard a lot about Steemit. Then after a lot of inquiries I came here. I read about the Steem dollar, I learned about cryptocurrency, I learned how to use steemit, I learned how to earn by steemit. But I did not fully understand what is "steem power"? how to use it? How much does it affect our account.
Is there anyone who can help me?
Who can tell me about steem power.
I really want to know about steem power.