Many people believe that the word “poles” when used for circuit breakers or switches refers to how many terminals are on the bottom. While it may be a helpful way to determine how many poles the product is, it is NOT the definition.
A Pole simply means how many circuits the product controls. Single Pole controls one circuit, a double pole controls two separate circuits within one product and so on.
The word “throw” simply refers to how many ON positions the switch has. So if you have a triple throw switch it has 3 on positions.
When you see SP3T it usually indicates three poles it can switch to.