Subdomains can be used for many different purposes. Like setting up another section for your website. It is not too complicated to set up a subdomain.
The steps would be as follows-
1. Login to the CPanel of your hosting account.
2. Scroll down to the domain section.
3. Click on Subdomains
4. Enter the name of the subdomain you want to create.
5. Select the domain name.
6. Click Create
This would create a subdomain with the name you specified. And this would also create a folder with the same name under the root directory where you could deploy your files.