You can make money by showing advertisement on your youtube videos. To show ads you need to link your AdSense account with your youtube channel.
Once you linked the AdSense account, follow the below steps to monetize the videos and start earning from it.
1. Log-in to your YouTube Account
2. Go to YouTube Dashboard
3. Click on monetization, available under Channel option on left side
4. Next, link your Adsense Account. ( if you do not have the AdSense account, first please open an Adsense account with google)
5. Now go to video Manager and click on Dollar Sign available next to your video
6. Click on ‘Monetize with ads’ options to start showing advertising on your videos
For more details refer the article at below link