Begin: Base Vectors

Step 1: Normalize vectors by dividing its dimensions to its length

Step 2: Calculation of dot product

Step 3: What it represents?

This value represents perpendicular projection of v1 to v2
or cos angle between these two vectors

Step 4: Self experimentation and comprehension

you can test it by giving max min an mid point values.
for instance,
when vectors are perpendicular to each other dot product is 0
when vectors are overlapping dot product is 1
this value will occilate between -1 and +1
if you do not normalize the values, then the value will be cos * length of v1 and length of v2.