The Act of Uniformity was an English statute, 14 Charles II c. 4 (1662), which required the use of all the rites and ceremonies in the Book of Common Prayer in church services.
For more information, see Conventicle Act.
(The '16 Charles II c. 2' nomenclature is reference to the statute book of the numbered year of the reign of the named King in the stated chapter. This is the method used for Acts of Parliament from before 1962.)
See also