I have been comparing several companies to start a reseller account with. On several of those sites they tell me that I have several IPs. What is the difference between having 1 or 3 IPs?

Well if you have mutiple sites and they need their own SSL certificate then they will each need their own ip address. That is the main reason.

Yes, there is no other reason to have multiple IPs except to host SSL certs.

well really it’s not ‘required’ that you have to have a dedicated ip for ssl. It’s just convenient. However, people do enjoy having dedicated ips.