Some popular examples of shoujo manga are Sailor Moon, Vampire Knight, Fruits Basket, and Cardcaptor Sakura.
Shoujo Manga focus around a a young female or a group of young female characters and their adventures. The setting may be sci-fi, fantasy, historical fiction, contemporary, etc. The emphasis is on the friendships, romances, and rivalries of the characters.
Although the stories are plot and character driven shoujo manga may also have action story elements.