BTC Halving is occur after every 4 years and after every Halving the BTC supply/reward become half for miners, that’s the simple concept to understand.
Sorry for being a broken record, but the
supply is not cut in half. The supply continues to increase every 10 minutes until it reaches 21 million. It is the
production that is halved. It is a common misconception.
The distinction is important because the claim that "the supply is reduced" it is typically followed up with a statement along the lines of, "and a lower supply causes a higher price." The logic is erroneous because the supply is not reduced.