which is the best advantage in PHP?

I have heard lots of buzz about PHP’s most amazing feature is it it’s hard to crack security features that enables developers to develop a

website that is which hackers can’t get hacked easily. Is it true?

I would say any language is as safe as the hands it is placed in.

Anyone can use a door, but not everyone remembers, or is able, to lock it.

PHP, Perl, ASP ... only as good as the server it's on, and the programmer's scripting.
If a server is not configured properly, many things can happen. This is an issue when
dealing with a shared webhost. If security is very important, you'll want to carefully
pick who is hosting your site, or host it yourself (for full control).