「お茶 (おちゃ)」 means "tea." This word refers to a popular beverage made by steeping dried tea leaves in hot water. The 'お' is an honorific prefix, making it more polite. You use it when drinking or offering tea.

茶(ちゃ)葉(ば)から作(つく)る飲(の)み物(もの)です。お茶(ちゃ)を飲(の)みましょう。