physics.body Parameters?

Greetings amazingly helpful forums peeps!

I’m here to ask for some angel to shed some light on the syntax of physics.body

 p_ball = physics.body(CIRCLE,ball_diam/2)

(Line of code taken from @Igntaz 's tutorial)

What is the requirements for whats in the ()? I know that it specifies what shape it’s(CIRCLE). Then after is the radius of the circle but what about an EDGE?

w1 = physics.body(EDGE,vec2(0,0),vec2(WIDTH,0))

(Line of code taken from @Igntaz 's tutorial)
Besides that EDGE is a static object, can someone clarify what all of the other “stuff” thats there is? Particularly vec2.
Also, anything else that I am ignorant of? (about this, for I am ignorant of a lot of things…)

Thanks again for your precious time and I’m tired so good night!