Web hosting is quite simply the provision of webspace.
In English, all websites are stored on giant computers called servers. These servers are online 24/7 and as you can imagine cost quite a bit of money to power and maintain.
When you buy web hosting you are renting a little section of a server to host your website. Bear in mind that for that fee you are getting access to the server, the electricity required to run it 24 hours a day, any hardware replacement and the team of staff it takes to maintain the server. When you think about it, your web hosting fees are incredibly good value.