The Fields page lets you configure colors that are used for the display of specific columns when the Lister is in Details or Power mode. For example, you could have the Type field displayed with a different background color, or the Size field in bold. For each column (if it's enabled), you can specify text and background colors, and select from bold, italic and underline styles.
The Reverse standard sort direction option allows you to change the way each field sorts by default. When the option is off, as is the case for most fields, the field will sort from smallest (at the top) to largest (at the bottom) the first time you click its column header. The same field will sort from largest to smallest if you click its column header a second time. For example, the filename field defaults to sorting A-to-Z on the first click and Z-to-A on the second. When Reverse standard sort direction is turned on for a field, you get the opposite: Largest to smallest on the first click; smallest to largest on the second. Date fields default to reverse sorting, giving you the most recent (largest date) files at the top on your first click. Size fields also do this, giving you the largest files at the top on your first click.
The Current sort field entry is a special set of colors and styles that applies to whichever field the file list is currently sorted by (or if multiple sort fields are defined, the primary sort field).
The list of fields allows you to see the field colors and states at a glance. If the checkbox is not set for a field then its colors, while visible in the list itself, are not currently enabled and will not affect the colors used to display files. If an arrows appears on the right of a field's name then that field is set to sort in reverse. The checkboxes and arrows are independent of each other; that is, you can enable reverse sorting without having to turn on special colors, and vice versa.