"The skirt is on the table."
Translation:Der Rock ist auf dem Tisch.
"am" (an dem) means "at the table" like - Wir sitzen am Tisch -- We are sitting at the table. You must use "auf" when discussing items physically on the tabletop.
In theory, it just sounds kinda funny. The subject usually comes first. If you said "On the table is the skirt." in English it also communicates the point, but nobody would ever say it like that.