Laura: hello, mother, i was—[ she makes a nervous gesture toward the chart on the wall. amanda leans against the shut door and stares at laura with a martyred look .] in the excerpt from the glass menagerie by tennessee williams, which element of drama is contained in brackets? stage directions narration dialogue dialect description

The words in the brackets are telling the actors what to physically do, meaning it would be a stage direction. 
It isn't dialogue because that is a conversation between two people.
It isn't dialect because that is how a person speaks. There is no speaking in the brackets.
It isn't narration because it isn't spoken allowed for the audience.
It isn't a description because that is too broad a term more often used for emotions.

Ienjoy; fan-girleverything of blood and bone