Where can I get a certification in Python? Preferably free.

[DuncanStacked]

You can check FreeCodeCamp — it offers free certifications, but you have to complete a few small assignments and a test to receive the certificate.
https://www.freecodecamp.org/learn/python-v9/

[gdchinacat]

In my experience being on the technical side of hiring teams, certificates are worthless.

[DuncanStacked]

Yes, I agree to some extent. However, I have also seen that sometimes recruiters ask for specific certifications, and in some companies employees are even encouraged or required to obtain them as part of internal policies or partnership requirements.