It's mean to call someone a braggart.
Jocelyn hears that from her brother Phil that he got a really good SAT score.
Jocelyn wants to respond to Phil.
Jocelyn tells Phil that she knew he could get a high score.
Jocelyn tells Phil that he is too proud of his score and a braggart.
Phil will feel that his sister believes in him.
Phil won't want to share his achievements anymore.