沏茶 means 'to make tea' specifically by pouring hot water over tea leaves and letting them steep. It's a separable verb (离合词): the verb 沏 and the noun 茶 can be split when you add a measure word, result, or aspect between them, like 沏了一杯茶 ('made a cup of tea'). You cannot directly put an object after 沏茶 — the 'tea' is already part of the word.