Find "Advanced Zone Editor" under "Domains" Category in cPanel.
1. Select a domain from the drop-down menu.
2. Kindly refer below image/example to add new TXT record.
Name: Fill in your subdomain or URL
TTL: Default is set to "14400"
Type: Select 'TXT'
TXT Data: IP address, example: v=spf1 include:_spf.google.com ~all (Google SPF)