If it only ran at one speed, it's a one speed.
It it ran at two speeds, it's a two speed.
Seriously, also look on the pump label at the RPM rating - if there's only one number 3450, it's a one speed. If there are two numbers - like 3450/1750 then it's a two speed.
A two speed pump also has 4 wires: red, black, white, and green. Red is usually low speed, and black is high speed. The white wire is common and the green is ground.
If you don't have the red wire, it's a one speed.
Best thing to do is replace the pump with the same as the current pump. Don't go with larger HP either. Your pipes will be unhappy.