hif to png conversion is used for the purpose of exporting or saving modern Hight Efficiency Image Files (HEIF/HEIC) to standard PNG format. In previous versions of Windows you even had to use a plugin to add support for .hif files to the system, but since Windows 11, you can just open and resave files with the default MS Paint.
Of course, you can also use one of the graphics editors for this, most now have or soon will have, support for HIF format.