Please What Sat, Act Reasoning Test Is?

I want apply into one University in USA, but they said you have to seat for SAT Reasoning Test, or ACT Test, Please is there anyone to explain this SAT and ACT test to me? How to register and seat for this test, i will be very grateful if you help me with this information.

Are you look for taking SAT/ACT exam in Nigeria in order to meet the requirement of USA college/university admission/enrollment?

Check the link i provided above. Good luck!