Sure, there are people who made different videos on youtube describing the details of Steem Power.

I will also explain here in text. Steem Power is the stacking version of Steem. When you power up Steem into Steem Power, your vote gets stronger. When you want to get the Steem back, you have to power down Steem Power and that takes 13 weeks, equal weekly payments.

Steem backed dollars, is a extra currency pegged to the US dollar. It is suppose to be valued around 1 dollar, so that if you want to hold "dollars", you can do it in Steem Backed Dollars and don't even need a bank account to do it!