It is a program for Apple's macOS that lets you search for files on your disks.

Features of Find Any File (FAF) 2
If you search for files by name, size, date, kind, and other directory properties, use FAF, because only then can you be sure that everything available is found.
FAF can also find text content if it's uncompressed, as in plain text files and even most binary files. And with the new option to include Spotlight results, it can even find text in compressed PDF, Word, and Excel documents if they were indexed by Spotlight.
FAF can not find metadata stored in files, though, such as image sizes, EXIF data, and GPS coordinates. If in doubt, see the manual or simply try out FAF for free.
Technical Details and System Requirements
Supported Operation System: OS X 10.11 or later