This is a term coined to identify things like jiggling breasts, cleavage shots, panty shots, bra shots, closeup shots of women's breast, legs, butt, etc., and mild nudity all for the purposes of "servicing" the audience and having no relevance to the plot or characters of a series. The term has a second meaning covering things like massive action sequences, explosions, fights, etc., but it mostly refers to the first meaning.
Self-explanatory. Series who's primary focus is fighting would fit into this segment. Yu Yu Hakusho and Ranma 1/2 are classified as fighting series. But if you can, then please select a more specific keyword instead, such as "Gun-Action" or "Swordplay"; maybe some day we'll completely split up this category into some more terms of this sort.
