Everything I say has to be qualified with a 'it depends on your exact needs' statement.
One of the best things about PHP is that it is free and open source (no I'm not an open source nutter), that means practically every hosting provider in existence offers it and offers it on a free or relatively cheap plan. This means you can pick among the best hosts for your site.
The stack that PHP is most usually found in is called LAMP (Linux, Apache, PHP, MySQL). The combination of technologies has been proven to be very reliable and efficient. Again all of these are open source and free so every host should have them for you.
PHP as a language is in my opinion relativley easy to get your head around. It's style makes it seem to me that it is aware of how real world programmers work and I just find it a sensible language to use.
Features wise PHP has never not been able to do a job for me. It is IMPORTANT though that you use PHP 5+ as going from 4 to 5 introduced many improvements especially in areas like OOP which after a short while using it you will most likely want to use.
Lastly I would say the support network for PHP is one of the best. From sites like DaniWeb to articles on NETTUTS etc it can help you in a jam.
PHP has become one of if not the most used language on the web, it wouldn't be a bad choice to use it (in my opinion).
All the best
Can someone tell me y PHP is good for making a website?
You need to think about all your requirements first, then look for a solution, not the other way around. PHP isn't a solution looking for a problem.