It's really hard to explain steem to new users.

But STEEM is a currency
SBD is a currency
These are basically money.

Steem power is locked money. It is like you can invest into something.
The more steem power you have stocked up the more your upvote is worth.
You can always take your steem power back into steem but that will take 13 weeks. you get 1/13 every week.

Steem power creates bandwith for you, so you actually can make posts and comments.

You have voting power what will go down every time you vote someone making your vote worth less.
But over time that voting power regenerates by itself.