It's a special case of the slope-intercept form because it is of the form y=mx
Generally, lines can be written in the form of y=mx+b, but in this case the b=0 which means it goes through the origin.
By the way, b is the y-intercept, and m is the slope.
y-intercept is when x=0
I have attached a graph of the line y=5x so you can understand it better.
