What is transfer fee paid?

Excuse me, could you please elaborate on what exactly is meant by the term "transfer fee paid"? Is this a fee that is incurred when transferring funds or assets from one account or wallet to another? If so, is it a percentage of the total amount being transferred, or is it a flat rate? Additionally, does this fee vary depending on the cryptocurrency being transferred, or the platform being used to complete the transaction? Understanding the specifics of this fee would be greatly appreciated.