(see also: Fill/Stroke Editor)
A solid fill is a fill that completely fills a closed vector object.
To apply a color fill, select the object, then use the color dropdown to select a color. This list will have reference to the color swatches you have.
Even-Odd Fill and Winding Fill
When you have a vector with path that self-intersects multiple times within the same element, it forces flexi to make a decision about which elements are filled and which ones are not. You can control this decision with the Even-Odd Fill and Winding Fill options. The Winding and Even-Odd fills are tools to help you decide which is correct, depending on the artwork. (additional reading: Self-Intersections)
The below image is a single path. Note how the line on the center-left overlaps the other lines.
Even-Odd Fill will alternate which sections are holes and which ones are filled.
Winding Fill will fill anything it determines to be an interior part of the design.
Wireframe
The Wireframe feature will convert the object to an outline, regardless of its fill. Wireframe will also completely ignore the stroke settings in the Stroke tab.
Wireframe Off
Wireframe On
Overprint
Checking Overprint turns on Overprint for that particular object. Refer to the article on Applying Overprinting.