As you know, halving is an update of the Bitcoin block where the extraction rate is halved.
It occurs every 210 thousand blocks, on average a block is created every 10 minutes, and should occur in 2020.
This data, however, depends on the hash rate, which if it increases then decreases the extraction time vice versa if it decreases then the extraction time increases.
Halving is important because it reduces the circulation of new bitcoins, in fact this is one of the causes of the probable price increase.
The next Halving will have to take place around block number 630 thousand, currently we can see here what block number we are.