Essentially, you are projecting V onto N and testing if this projection is pointing in the same direction as N.

V•N means to take the dot product of V and N. This gives us a scalar number which tells us the magnitude of this projection. If this magnitude is positive, it is in the same direction as the Normal vector.

Watching 3Blue1Brown's video on dot products helped me understand this: https://www.youtube.com/watch?v=LyGKycYT2v0

Essentially, you are projecting V onto N and testing if this projection is pointing in the same direction as N.

V•N means to take the dot product of V and N. This gives us a scalar number which tells us the magnitude of this projection. If this magnitude is positive, it is in the same direction as the Normal vector.

Watching 3Blue1Brown's video on dot products helped me understand this: https://www.youtube.com/watch?v=LyGKycYT2v0