As you can see PHP is installing version 5.5.20-2.el6.remi from the remi-php55 repo! Once you have hit Y to confirm the install restart apache and magical unicorns you have a better version of PHP!
You can also change your mind in the future by going back into the remi.repo file and enable a different PHP version and then run yum update and if you have moved from 5.5 to 5.6 it will upgrade PHP for you. If you want to downgrade for any reason you will need to remove PHP (sudo yum remove php*) and then reinstall the PHP modules you want.