pkg_backup_64.rarENGLISH
MySQL 5.6 got deprecated and removed lately from FreeBSD ports and pkg repos therefore you are not able to install it via pkg install mysql56 or from ports.
You can still install it manually, you have to upload the attached package files to anywhere for example /usr/pkg_backup_64 then you can install the packages via pkg add command as:
pkg add /usr/pkg_backup_64/mysql56-server-5.6.51.pkg
pkg add /usr/pkg_backup_64/python27-2.7.18_2.pkg
etc..