The slope of a velocity-time graph represents acceleration.
The slope of a distance-time graph represents speed.
The slope of a line on a position/time graph, represents rate of change.
The slope of a line on a position vs. time graph would represent the a velocity of the object being described.
The slope of the speed/time graph is the magnitude of acceleration. (It's very difficult to draw a graph of velocity, unless the direction is constant.)
magnitude of acceleration at every point on the graph
speed (magnitude of velocity)