What does fixed monthly fee mean?

Could you please clarify for me what is meant by a fixed monthly fee in the context of cryptocurrency and finance? I'm trying to understand if this refers to a set amount of money that is charged on a recurring basis, regardless of the level of activity or transactions within a given month. Is it a fee that's typically associated with a particular service or platform, or can it apply more broadly? Additionally, how does this type of fee compare to other pricing structures, such as variable fees or percentage-based charges?