You can select multiple objects and move them around as one. You can also turn a selection into a group, so that they act as a single item.
You can select multiple objects, or extend / reduce your selection by either Click+Dragging around the objects, or using Shift+click. The top status line tells you how many items are in your selection, and a pale blue dotted outline indicates the selection.
If you want to create a group, simply click Group in the toolbar next to the selection.
You can resize your selection or group by dragging on the corner selection handles. With multiple shapes selected you can resize them around the center when you hold down Shift.
Other options in the toolbar enable you to duplicate your group or selection, or (click ... at the right end of the toolbar) cut, copy, paste or delete them.
You can select a single object inside a group by double clicking it, and then edit it. For example edit text inside a group, replace a photo or edit Shapes.
Check out this tutorial for more info...