[tseres]

mx - The middle of mass x value
my - The middle of mass y value
x1 - The left most corner’s x value
y1 - The left most corner’s y value
x2 - The right most corner’s x value
y2 -The right most corner’s y value

I don't understand what they are trying to say with "left/right most corner's x/y value"

when the camera sees colour to track it, it is just like a giant blob of pixels of the same colour (what it is tracking).

mx=the middle x value of the blob. it's the position on the x axis of the middle of the blob

my=same as above, except on the y axis
x1=the x value of the top(?) left corner
y1=same as above except on the y axis
x2=the x value of the bottom(?) right corner of the blob
y2=same as above except with the y axis

for example, the coordinate of the top left corner of the colour blob would be (x1,y1) and the bottom right corner would be (x2,y2)

hope that helps!