The area under a velocity-time graph gives the displacement. The velocity-time and acceleration-time graphs for common motions are shown below.

GCSE Eduqas Using and interpreting graphs - Eduqas Distance-time and displacement-time graphs- Higher Using graphs is not just about reading off values. In real-life contexts, the intercept ...

But if you calculate the acceleration without the graph, you are explicitly stating that the y-intercept is zero---which it might not be. So there are some actual reasons for making a graph.