Various 'form' files often use .frm extension to denote this special type of document, so in this sense frm to pdf conversion is probably related to attempt to export these as PDF document. This can be usually done via print function when you open and fill the forms either online or in a specific program.
But many other formats use .frm extension as well, so perhaps this might also be related to something entirely different.
Updated: September 26, 2023