Does any of you guys know this sub? it says that has XLR-3-31 and XLR-3-32in put, what kind of connections are those?

I believe these are types of 3 pin, balanced connectors. Although I don't know the difference between the two model types you mention. These are normally used in connecting to pro audio gear, such as you would find in a public address system or gear for live performance.

The equipment on both sides has to support balanced connectors so it's not often used in home gear.