So if I have btc i can't save it in myetherwallet? Is it highly recommended for using hardware wallet?
Correct. Only ETH and ERC20 tokens can be saved on myetherwallet. For BTC you can download a wallet to computer, get a paper wallet, get a hardware wallet or keep it on the exchange. It really depends on how much you have. A hardware wallet like nano ledger s is about 100USD with shipping, so it depends on your stash.