Female. If it has ever been in a tank with a male it might already be pregnant.
This goes only for the anal fin. Not the other fins. There are guppy strains where both genders have a pointy or rounded edged dorsal.FYI, to tell the difference between male and female is that usually the male is smaller and has pointed corners of the tail. The female is usually larger and has more "curved" tail corners. Males also have larger tails and a brighter in coloration.
Good thing you mentioned "usually". For there are guppy females that are pretty colorful.Females are usually duller in colour with a gravid spot, males are more impressively coloured with a pointed anal fin