The statement refers to the various taxation policies imposed by the British government on the American colonies in the 1760s and early 1770s. While it's not accurate to say that the British taxed everything except tea, one of the most notable tax laws related to tea was the Tea Act of 1773.
This act allowed the British East India Company to sell tea directly to the colonies, effectively reducing the price of tea but maintaining the tax on it. This was seen as an attempt to undercut colonial merchants and enforce the principle of Britain’s right to tax the colonies.
The growing discontent over British taxation, including the tea tax, culminated in the Boston Tea Party in December 1773, where colonists protested by dumping an entire shipment of tea into Boston Harbor. This act of defiance was part of the larger conflict that ultimately led to the American Revolutionary War.