You need to exchange bitcoin into fiat currency, you cannot just cash out or transfer the money to bank account just like that.
I suggest avoid using paypal to sell it, because it is reversible and some people here do chargebacks and try to scam your money.
localbitcoins.com
coinbase.com
kraken.com
Kraken and localbitcoins are fine, coinbase is okay too, but they have quite often problems and their support is horrible.
They do not look into your problem before you make a Scam accusation or so on about them. The plus is quite low fees when buying with credit card, not many providers offer such low rates.
Bitstamp is good as well, from what i have heard.