First you need to put it in the correct order, isolate y.
4x+6y=12 subtract 4x
6y=-4x+12 divide by 6
y=-4/6 x+12/2 simplify
y=-2/3x+6 so now the equation is in slope intercept form which is y=mx+b
m=slope
b=y-intercept
So, the slope is -2/3 and the y-intercept is 6