Both .fla and .xfl files are related to older Adobe Flash content and most likely describe some kind of export between then projects and exchange format, or something similar. Such export might be little challenging to do nowadays and probably used for a very specific purpose or reusing of old materials.
Adobe Animate supposedly still can work with .fla files, but it might not be able to export to XFL format. Still, Adobe software is most likely your best choice in this matter. You can always try to reach out to their support or online community for further assistance.