PHP is categorically a server side scripting language most liked among developers and now users too.It has the capability of being embedded with HTML and therefore it is a very popular programming language for developing complex and robust websites.
As it can be embedded with HTML so can be used in any language for the further updations. PHP that is why used by many developers for any updations, improvement in the Website. So that is why PHP helps you in redesigning your site.
How it can be helpful:

1. if the framework needs some changes, due to PHP embedded features it can be possible in very easy manner.
2. if framework needs to update in any field, then PHP can be very helpful.
3. A PHP development company can easily give you the features for all kind of resigning and can be useful in creating a perfect seo friendly site.