the operation of extracting the square root of a number and then squaring
it can lead to minor rounding errors due to
working with floating point numbers

rparks52 is right (assuming "p = 1" is "product = 1".)

This process is called initialization; where a variable is assigned for later parts of the code to use.
for example : arr = [1, 2, 3, 4, 5]

1. product = 1
2. arr[0] --> product = product * 1
3. product = 1
4. arr[1] --> product = product * 2
5. product = 3

Following this process, regardless of what integers/floats are in the array, they will definitely multiply each other.

Okay this one make me laugh, i imagined this as a someone slapping an object twice on both sides