Isn't the voltage reading in this image wrong?
The right-hand rule actually uses conventional current, not electron current.
It's a lot clearer if you look at the the Lorentz Force equation that the rule comes from:
\$F = q \vec{E} + q\vec{v} \times \vec{B}\$
If you look closely at the \$q\vec{v}\$ term, you will notice that it actually dictates you point in the direction of the movement of the charge. However, the electron charge q is negative which ends up reversing the direction. Super confusing. I know.
But in this way, it can also be applied to positive charges that are moving like protons.
So if you follow this, a force is exerted on the electrons into the page which means that the right terminal of the voltmeter will be more negative than the left terminal.
Personally, the image of the voltmeter is so blurry I have no idea what anything on it is. Presumably, the left side of the dial is negative, the right side of the dial is positive with 0V being the center.
It would appear that the left terminal is the positive terminal and the right terminal is the negative terminal of the voltmeter (which is pretty common).
So it looks like it all checks out to me.