You are Malvolio. Malvolio gets a letter from who he thinks is the wealthy countess Olivia, which suggests that she loves him. (It's a trick-people that he;s upset because of his snooty behavior have decided to spite him.)
So, the letter suggests that Olivia will show favour towards Malvolio and by doing that he will have greatness (high status) thrust upon him, and he is pleased to read this.
