SPF records are used to validate that the mail server sending your emails is authorised to do so for your domain.
SPF is enabled by default on all accounts but you can change this setting within cPanel under the "Email" section and clicking the "Authentication" icon. Only change these records in your DNS editor within cPanel if you understand the impact of what you are changing.
With SPF enabled all emails you send will be tagged to notify any receiving mail servers that they should only trust emails sent from your particular mail server. If any email has your domain as the originators address this is the only mail server they should trust as being genuine.
This is a very useful anti-spam tool and is very hard for the "spammers" to forge. Therefore it gives a better level of confidence in any anti-spam software or processes that your email is genuine.
We recommend you use SPF in conjunction with DKIM as authentication for your emails for even greater levels of "anti spam" confidence.