What is the best free tool to edit videos on the MacBook Pro?

On Macbooks I highly recommend using iMovie since it came free with macOS and it's very system/user friendly. It has all of the "core" things you may need to edit a video or a vlog ;)

Apple has hit a home run with this amazing application

Hitfilm is great!!! It has a lot of features that people pay a lot of money for in the creative cloud with premiere and After Effects.

Think about Premiere but free. You can do almost anything with the product and they have excellent tutorials

As well as being the industry leading in color grading, DaVinci Resolve is now a fantastic editing tool which rivals Premiere, it should also run great on a Macbook Pro which is a plus, as the only reason I'm personally not using it is that Premiere just does a better job on Intel Integrated Graphics on windows