SPF stands for Standard Policy framework. It is being implemented by many Hosting providers. Hosting providers need a SPF record, so that a email can go through their network. It is an attempt made to control bounce back emails. It allows the e-mail address owner to specify the mail servers which will be used to send mail from their respective domain to prevent sender address forgery. The SPF record makes sure the Remote email server will allow mails on your server from your domain name only. It helps fighting against spam emails.
Its mostly used to create SPF record for a particular domain name so that you will not receive any bounce back emails that are not sent by you. The SPF record can be setup and managed for the respective domain name from Plesk or cPanel –> Email Authentication.