Struggle with finishing project

So, Im supposed to define the member functions of the class that I created in another .cpp file. I already have the header (.h) file but when I go to build the project, the build fails and states: ld: 7 duplicate symbols for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation).

I am new to c++ so I don't really know whats wrong.