Your website is made up of many files (e.g. text, media, code, etc), these files need somewhere to sit on the internet in order to displayed and viewed.
Web hosting is the leased internet space your website files sit on. By having your website hosted, you lease your own little piece of the world wide web which enables anyone with access to your online address (URL), access to your site. So instead of having to send files to people each time they want information, they’re able to simply type in your websites URL e.g. www.einsteinwebdesign.com.au and view it all there.
In summary, without web hosting you won’t be able to set up your website for others to view online.