Yes. I think that's right. That means that there is a lien on the property, a loan that my ex took out where she is the sole borrower, and I as the co-owner only have the right to know what the total loan can be, not what the balance is.you are either listed as a borrower which would allow you access to information regarding the loan or you are not a borrower and you would not have any rights to the specifics of the loan.
a mortgage is used by many people to mean many things. In it's strictest sense it refers to a lien on a property due to a loan. If that is the use of the term in your situation, it means you signed a mortgage allowing for the lender to register their security interest in the property based on the underlying loan.
many people refer to a mortgage as the loan itself. While that is accepted in some circles, I don't think that is how the lender is using the term.