Your hosting is backed up automatically, but it's good practice to take your own copy before big changes.
Quickest: WordPress Toolkit
In cPanel's WordPress Management, select the site and click Back Up / Restore › Back Up. You can download the backup file once it's created.
Fully manual
1. Files
In File Manager, select the WordPress folder (usually public_html), click Compress to create a zip, then download it. Alternatively, download the folder with FileZilla.
2. Database
- Check wp-config.php for the database name (
DB_NAME). - Open phpMyAdmin in cPanel and select that database.
- Click Export, keep the Quick method and SQL format, and click Export (or Go).
Keep both the files and the .sql file together. Store backups somewhere other than your hosting account.
Restoring
Upload the files, import the .sql file into a database, and make sure the database details in wp-config.php match.