XYplorer Beta Club

DBF is a format that is still used by a number of programs.

See:
https://en.wikipedia.org/wiki/.dbf
https://gis.stackexchange.com/questions ... shapefiles
https://mxd.codes/articles/what-is-a-sh ... bf-and-shx
https://www.systoolsgroup.com/dbf/

Previews aren't generated by XY, they're done by preview handlers installed on your system. You'll have to find and install one for .DBF.