We can earn bitcoins in many ways

1) By Mining 

We can mine bitcoins. It was easy in starting in 2009 - according to figures it was done in every 10 min. But now a days you need expensive instruments and too much time to mine.

2) Games - Gambling and Casino Games

There are so many games available in market using which you can earn BTC.

3) Job for BTC

There are so many place or freelancing websites who offers BTC for the job as a currency. Check here too /r/Jobs4Bitcoins on Reddit.

4) Trade with BTC

There are some websites where you sell things for BTC. Like you can sell handmade things for BTC.

For cash out bitcoins there are more than 1 ways too.

1) Third Party Broker Exchange

2) Peer to peer

Hope this will be helpful.

Thanks