In this screen, you can customize the Fonts used by the File Manager and other KDE applications.
The "Font Size button selects between Small/Medium/Large Font sizes.
The pull-down "Standard Font" list allows the standard (proportional spacing) font to be chosen.
The pull-down "Fixed Font" list allows the font for displaying text with fixed spacing to be chosen.
The pull-down "Default Charset" list allows the default character set for displaying text to be chosen. If "Use Language Charset" is chosen, no default character set will be selected, and the character set appropriate for your Language setting will be used.