and what will happened after halving? what it means? after halving difficulty will increase or decrease?
The difficulty will be increase since the blocks is 12.5
BTCNo. The difficulty will not increase. There will only be 12.5 BTC every 10 minutes, period. No matter what the difficulty is.
I presume the difficulty will decrease because many people will not be able to pay for the electricity mining only half of what they are mining now.
Until the price doubles, then they will turn on their rigs again.