What exactly is meant by "unlimited accounts"?

It’s mentioned as a difference between free and pro, but there is no explanation as to what it means.

When using Free version, you can use only 2 email accounts. With PRO version you can use as many accounts as you want.

Ok. You should make the 2 accounts limitation more clear in the comparison. Just saying unlimited on the Pro side doesn’t tell anything about the limitation on the free side.