You've written code that repeats. Maybe you calculated averages three times or printed headers in five places. Each copy creates a problem: if you fix a bug, you hunt down every copy.
Functions solve this by letting you name a chunk of code and reuse it. Write the logic once, call it anywhere. Change it in one place, the fix applies everywhere. I'll show you how to define functions, pass data in, get results back, and organize code.
You'll go from repeating yourself to building reusable pieces.