When you have SP (steem power) you can chose to give (delegate) it to another steemian.
So if you have 50-SP (which makes your UPvote amount either zero or one cent at 100%) in your wallet and someone delegates you say... 1000-SP.. now your SP voting for UPvotes could be worth 25/cents at 100% (just an example price amount)
The delegation is given to you and when you UPvote, it makes you voting power higher and more valuable.
You're like the coolest grandma ever!