As you should already know you can vote on people's posts if you like them.
Now, this is not unlimited. You start with 100% votingpower.
If you make a vote on 100% (minnows always do, whales and dolphins with more capital can choose to do 1%(of that 2%) for example) you will use up 2% of your votingpower.
Each day you regenerate 20% votingpower.
The lower your votingpower is, the less weight your vote carry so the lower the reward .
Where to check your amount of votingpower?
Got to https://steemd.com/@username
On the left side you have your votingpower in the list.
Happy voting!