We call this a "debit-style" card, which means that your experience will be pretty much the same as with a regular debit card: you can only spend the money that's in your Step account, purchases are taken out of your balance in real time, and you can see your deposits and spending all in one place.
There is no way to overspend. There are no overdraft fees. And you don’t pay interest.
At the same time, you get the fraud protection and credit building benefits of a credit card!