C/C++ is a term which refers to two closely allied computer programming languages.
W3 Schools says, "C is one of the most popular and widely used programming language, used to develop system application software."
W3 Schools also elsewhere says, "C++ is a general-purpose, middle-level programming language, with high and low-level programming capabilities, and this is one of the most popular commercial programming languages."
Both of these W3 Schools sites offer excellent introductions and tutorials.
I'm working on some C/C++ programs, but I don't have any ready to put up on this site yet. But, you can explore these two W3 Schools sites for additional information.
C/C++ can be rather complex and difficult. To make things a little easier, I'm also using the Qt Framework with C/C++. Their site says, "Qt is much more than just a cross-platform SDK - it's a technology strategy that lets you quickly and cost-effectively design, develop, deploy, and maintain software while delivering a seamless user experience across all devices."