Open Source software actually means a lot of things to the average user, whether he or she knows it or not. It means that you can sell or give the software away to anyone you like. It typically means you don't pay a lot for the software. Anyone else with the same software can give you a copy of it, for that matter. You can sell or give away your changed program.
Much commercial software is high quality.
Some of it is even better than Open Source software. If it doesn't work the way you want, you can't change it. You can suggest changes that may or not get rolled into the next version. You'll probably have to wait months or years for the next version. You can't give the software to your friends.