You can change whether to clip the content or to add scrollbars when the content of the parent box (child elements) are too big to fit in the parent box from the overflow tool on the Style bar.
The overflow is not clipped. The content renders outside the element's box.
The overflow is clipped, and the rest of the child elements will be invisible.
The overflow is clipped, and a scrollbar is added to see the rest of the child elements
In the editor, you can use the scroll bar to control the display position. This bar will not be visible in the preview/production site.
*If you are using a mouse, you can generally scroll vertically by holding down the Shift key.