To get the ball rolling

This idiom simply means ‘to begin something’.
When you start a new project, the task in front of you can seem very big and difficult to achieve. However, once the first step has been taken, things often progress more smoothly.
Consider the case of a community group who are trying to have a playground built. One member may say to the others, “Okay. Let’s just get the ball rolling on this. I’ll call the local government and set up a meeting.”