for what purpose c is being used?(for making computer softwares or for what)

Answer 1

It is mainly used in operating system related softwares or system softwares as it is fast to execute.

Answer 2

C is mainly studied to understand the computer, how it works. C++ is a super set of C which is usually used instead of C. C + OOP = C++ (OOP means Object Oriented Programming). While developing OS, the burden of OOP is really unnecessary, that's why C is usually used in OS and system softwares. Beside this, C has got some other purpose, like Python developers might use C for some purpose, etc.