The _alpha parameter is set as a percentage between 0 and 100, so setting the alpha to a value of 90 would mean that the snowflake is 90% opaque. To set a random opacity for the snowflake, the section dealing with _alpha generates a random decimal and then multiplies it by 100 to assign a random alpha value.
Like the _alpha parameter, _xscale and _yscale are percentages set by the numbers 0 to 100. Rather than generate a separate random number for each, instead we assign a single random number to the variable size, and then use an if statement to determine that if the value of size is greater than or equal to 25 but less than or equal to 100. This ensures that the snowflakes generated aren’t too small to see. If the snowflakes meet those criteria, then we set the percentage of the _xscale and _yscale parameters to equal the value of size. If not, then an else statement sets the scale to 90%.
