In some programming languages like C,C++,c#,Java,..etc when the code is compiled then the code is converted into another form in order to execute it. Does the Apache do the same or just it executes it without any conversion?
Apache doesn't do anything except handle the incoming request and serve the resulting output. Everything else is done by the PHP interpreter which pre-compiles the PHP code to a bytecode form, and then executes the bytecode instructions.
Apache is just a webserver that may or may not be running with PHP as a module. It's better to think of the webserver as a mere mediator between the frontend and the php binary.
The latter is compiled, yes, but it runs your code without compiling. It is an interpreted language.
There are ways to accelerate php processing using some opcode cache or just in time compilers, but default PHP doesn't deal with that.