The easiest way to see what a white-label is is with images.
There's the well-known brand:
You could create your own and be a small brand:
You could be a white-label and sell another brand (usually the well-known brand):
(*) These cans are white-label cans selling Del Monte peas.
You don't own anything as a white label and you can lose everything by a snap of a finger if the well-known brand decides to drop you or if you have issues getting paid.