Question

What does it mean the graph doesn't have an acceleration

Answer 1

Can you be more specific please?

A graph can be time vs distance, time vs speed, and time vs acceleration.

For a time vs distance graph, you can tell there's no acceleration if the line is constant.

For a time vs speed graph, you can tell there's no acceleration if the line is perfectly horizontal

For a time vs acceleration graph, you can tell there's no acceleration if the line is always at 0!