What language we can use instead of PHP

Answer 1

Basically any language. Most have frameworks that can be used in the Backend.

Here you have a couple of comparisons:

https://gearheart.io/blog/7-best-frameworks-for-web-development-in-2017/
https://www.pixelcrayons.com/blog/web/best-web-development-frameworks-comparison/

Answer 2

ruby on rails
python's django