SPF stands for Sender Policy Framework. The purpose of SPF records is preventing forgery of the senders address of e-mails. The domain owner can set this record to permit the Ips or servers that can send e-mails with this domain.
You can find information about how to set up a SPF record here.
If you have booked a hosting package with us, you can find further information how to set up a SPF record here.