The Array tools create multiple copies of an object arranged along a line or arc.
The the source object (the to be copied) can be picked from your drawing or can be a symbol loaded from your filesystem or the cloud. This object must be a group; if the selected object is not a group (or a symbol) a group will be created from that object before the copies are created. All of the copies in the array will be instances of the original group.
The Linear array tool created copies arranged along a line.
The Radial array tool created copies arranged along an arc.