Simple color code question

This is from a scoreboard’s config.

Scoreboard.cPrimary = Color( 32, 95, 132, 150 )

^ There are 4 numbers for colors within that bracket and every color schemer I can find is RGB

What’s the 4th one indicate? and is there a website that can lay out 4 numbers for a certain color to be defined?

Its opacity or also called alpha.
0 = invisible 255 = fully visible

Okay thank you!