anyone can tell me ? thank you
If you have exclusive control of say 10 bitcoins (private key / mnemonic seed) and hold them through the fork then you'll naturally have 10 "bitcoins" on each branch (10 BitcoinCore-coins and 10 BitcoinCash-coins if you will). After the fork, if you are careful (use trustworthy guides and services), then you'll be able to move the 10 coins of one branch without moving their twins on the other branch (see: "replay attacks"). If you only care about one branch then you can sell the coins on the other branch.
Of course, it would be extremely confusing to call both of these assets "bitcoin" so at least one branch will need a new name and ticker. While imperfect, the most popular assignment is currently:
- For the Bitcoin Core fork: "bitcoin", "BTC"
- For the Bitcoin Cash fork: "bitcoincash", "BCC" (caution: conflicts with BitConnect Coin)