In this quote, Don John is responding to news he has just heard from Borachio. Borachio tells him that he was perfuming a room when Claudio and the Prince came in, wrapped up in an earnest conversation. Borachio "whipped" behind a tapestry and was able to eavesdrop. He learned that the prince was planning to "woo" Hero that night and give her to Claudio as a bride.
Don John is pleased to have this tidbit of news. His quote means that he feels Claudio, the "young upstart," has enjoyed (had "glory" in) blocking him from gaining the upper hand over his brother. Therefore, Don John is glad to have information which he can use against him. Don John wants to do whatever he can to "cross" or thwart Claudio in his goals, and he recruits Borachio to help him.
The quote shows that Don John considers that he has been deliberately injured by Claudio. He is angry, perceives Claudio as his enemy, and feels justified in seeking revenge against him any way he can. Don John is a malevolent figure who doesn't like to see other people happy. He does everything he can to ruin the marriage between Hero and Claudio and almost succeeds with his evil plots.