Google makes money selling advertising space. Everytime you search Google, ads are shown at the top and bottom of the search listings and when you click these Google gets paid. Google earned $32 billion in ad revenue in 2018.
You can earn money by placing Google Ads on your website for you via Google Adsense.
Google will then look at your web page and place the appropriate advert on your site. For example if your site is aoutb property, Google will place adverts related to property on your site. When a visitor clicks on any Google Ads on your site you get paid.
The amount you get paid various enormously. To earn decent money you will need thousands of visitors to your site each month. From experience you could earn 5p to 30p a click. If you are lucky enough to have a high traffic site this could really add up to thousands.
In 2003 myself and my brother launched a property site called www.houseladder.co.uk which still attracts hundreds of thousands of people each month. This sites primary income is from Google Adsense.
The second way to make money with Google is via YouTube. Google owns YouTube and makes money via the platform by placing adverts before and in videos using the Google Adsense system.
You can make money by creating your own YouTube channel, uploading videos and linking your channel to Google Adsense.