Source code refers to the statements created by a programmer using a text editor.
Source code is human-readable, for anyone who understands the conventions used by that programming language (‘C’, ‘C++’, etc.), but can not be executed by a computer’s processor until it has been compiled.
The term binary code, by contrast, is applied to the compiled instructions contained within an executable file.
Binary code is not human-readable and can only be ‘understood’ by the computer’s processor when the program is run.