How to run Arduino from Raspberry Pi

I was looking for a way to connect a raspberry pi and arduino together and then have the main python code control the arduino or at least open a file that will run an arduino program. If you know how, can you please explain the procedures.

Thanks,
Disen

So the Arduino does something, but you want that to be triggered by the python program running on Raspberry PI, right?

Something like this?

yes thats exactly what I was looking for. I am going to try this on my jetson nano with servo motors.

Thanks!!