The Squeegee tool allows you to move multiple objects below a horizontal plane in unison. This is a great way to move your content all at once if you need to add or remove content. You can use the tool to push all of the content below the Squeegee line down to create some blank space, or pull all the same content up to close a gap.
Here's a demonstration:
With this tool, you can select an object and then click and drag up or down on the following icon:
The standard operation for this will be to move any object below the top of the one you've selected. There are a few modifiers for this as well.
If you hold Option/Alt and then drag on the icon, it will also move any objects that intersect with the horizontal squeegee line. See below for an example:
You can also double click on the icon to automatically select all objects below that point.