The fork is a change in the algorithm rules of the "centralized" currency and aims to improve the Network Difficulty Adjustment Algorithm.
The new algorithm change expects to adjust the hashrate difficulty to reach an average block interval of 600 seconds.
That changes in the algorithm leads to a derivation of the main chain, and a new coin is created, in which one of the coins continues with the old algorithm, and the other one uses the new algorithm.
When the fork happens, the old coins will exist in both chains, leading to a doubling of coins.