Merry Christmas to you too @L3X; if you are using the uClibc image you can find PHP on AlexT's repo. If you haven't already, you will find instructions on how to set it up in Galileo Package Repo Configuration Instructions. In case you are using the eglibc image, then you will have to build the PHP package from source. You will find the source in PHP: Downloads, once you download it, decompress it and you will find the installation instructions in the INSTALL file.
I've tried to install AlexT's repo and everything's installed properly. Now i've tried to access my test.php file from browser like localhost/test.php -->> I've got an 403 - Forbidden. I mention that my test.php has 777 permission. Any ideas ?