cPanel is the control panel used to manage almost everything about your hosting account - files, email accounts, databases, and more.
To log in, go to yourdomain.co.za/cpanel or yourdomain.co.za:2083 in your browser (or use the direct link your hosting provider emailed you when your account was set up). Enter the cPanel username and password provided to you - these are different from your website's admin login or your client billing login.
If you've forgotten your cPanel password, your hosting provider can reset it for you - for security reasons, they generally can't just tell you your old one.
Tip: Bookmark your cPanel login link so you can find it quickly next time you need to upload files, check your email settings, or view your website's statistics.