Steem Power gives you a stake in the company. In essence your vote is like Proof of Stake or "mining" to compare it with Bitcoin.

The more Stake you have the more value your vote will add to the value of someone's post. You also earn (based on the value of your stake) by curating peoples posts. That is, the voters are a given a share of the "money" that each post makes.

I would suggest that you search for some videos that explain how all of this works and watch them. In the meantime I will upvote your comment with 10% the value of my stake and lets see how much value it gives you!