Information about colliders for Cocos Creator can be found at: Colliders
The collider gizmo is used to display the position and size of the collider in the editor. Select any node with a collider component in the Hierarchy panel to see its gizmo in the scene window:
For all colliders, the collider can be resized by selecting and dragging these squares with the mouse. The following figure shows how to resize colliders, using the box collider gizmo as an example.