Currently, there are 18.33M XMR coins available. While some coins, like Bitcoin,  have a supply cap, there is no maximum limit for how many XMR coins can exist. The Monero block reward is dropping gradually, until Monero reaches the “tail emission” phase in May 2022. During “tail emission”, the block reward will remain at 0.6 XMR, and approximately 432 XMR will be created each day as long as Monero exists.