'Tea' as a noun means gossip or insider information — 'what's the tea?' = 'what's the gossip?'. Originally African-American Vernacular English and drag culture (where 'T' stood for 'truth'). Now mainstream Gen Z slang. If your teen asks 'what's the tea?' they want the latest news on whatever situation is being discussed. Harmless conversational vocabulary; only worth attention if 'tea' consistently involves cruel gossip about others.