A more thorough explanation:

The Act of Supremacy was a law passed in England during the reign of King Henry VIII in 1534. It declared that the English monarch was the supreme head of the Church of England, which meant that the king had authority over the church and its affairs.

The Act was passed to counteract pro-Catholic legislation enacted during the reign of Mary Tudor. It was confirmed in 1559 during the reign of Queen Elizabeth I.

One of the powers that the Act gave to the monarch was the ability to issue injunctions relating to ecclesiastical affairs. This meant that the king or queen could make decisions about how the church was run and what its practices should be.

For example, if the monarch wanted to change the way that the church conducted its services or how it appointed its leaders, they could issue an injunction to make those changes happen.

The Act of Supremacy was an important moment in English history because it established the Church of England as a separate entity from the Catholic Church and gave the monarch significant power over religious matters.