When you split code across files, you bring one file's functions into another with import — using the file name without .py. If helpers.py sits next to main.py:

# main.py
import helpers
print(helpers.clean("  ada  "))

Python finds modules by searching a list of folders. You can see what it knows about your setup:

Most beginner imports "just work" when files are in the same folder. If you hit a ModuleNotFoundError, it usually means the file isn't where Python is looking — check you're running from the project folder.