The term, “halving” pertains to the number of coins received by miners when they add new transactions to the blockchain that are cut in half. The process of halving diminishes 12.5 Bitcoin to 6.25. The process will repeat again every 210 blocks until it reaches the last Bitcoin, which will be mined in 2140.
Worthy of note, the previous halvings that had taken place saw bull runs in which meteoric increases in Bitocin’s value had been evident. This had transpired back in 2017 following the reward decreasing from 25 coins to 12.5 in 2016.
The possible theory that surrounds this is not at all complex. The fewer the Bitcoins being created and released, the more valuable the ones that are available in circulation becomes.