Gradient is synonymous to slope.
y = 6x + 5 is an example of a slope-intercept form of a straight-line equationl.
The slope-intercept equation is like this:
y = mx + b
where : m = slope ; b = "y-intercept"
y = 6x + 5
6 is the slope
5 is the y-intercept.
Since slope and gradient are synonymous, 6 is the gradient of the above equation.