SUPER new to cameras here. I posted a few weeks ago with some questions on the basics in picture taking with a Rolleiflex that my Grandfather used way back in the day. Fast forward to today and I'm watching this video:

https://www.youtube.com/watch?v=-RzlQ6OXXQU

He says to match the iso of the camera to the light meter (I'm using the pic related app), take the light meter reading, then change the shutter speed and the f/stop accordingly. I guess I'm a tad confused on that part. I believe (again, super noob here) my iso and shutter speed are one and the same thing on my camera (Rolleiflex 3.5B). Should I dial in the speed of the film on the light meter and the set the shutter speed and f/stop accordingly?

And one last question. My camera has a lever that will lock in the shutter speed and f/stop and will hold a certain EV value. What exactly is an EV value? Is that some numerical value of the light entering the camera at any given two values of aperture and shutter speed? If I lock them together, will all of my pictures have the same exposure no matter where my f/stop is because it will change my shutter speed with it?

Sorry for the more than likely cringe worthy questions.