Excel

Hi Shane, welcome to the forum, thank you for your post; the writing/editing and using of macros is covered comprehensively in our Excel Advanced and Excel VBA courses.
But to answer your question; a macro is a recording of mouse clicks and/or of keyboard entries which are recorded by Excel and played back (like a tape recording) whenever required, a macro is usually recorded to undertake mundane or repetitive tasks, either simple or complex, which saves continuously resolving the function manually.
I hope this has helped, if so please click the Resolved link, best regards Pete.