In literature, characterization is the way the narrator or author lets the reader known the characters' personality, appearance, values, etc. Characterization can include multiple techniques such as using direct description (direct characterization) or the character's actions, thoughts, words (indirect characterization). In the case presented, one action is being used to show the personality or behavior of Marcie as the narrator describes "Twisting her braid between her fingers, Marcie jumped whenever anyone entered the room" and this suggests Marcia is either excited about people that enter to the room or nervous. Thus, the method of characterization, in this case, is action.
Glossary, is the name for the list of important words (and their definitions) at the end of a non-fiction work. They are meant to help the reader with understanding the material and can sometimes appear in fiction work as well.