The process is to select an object and select any one of the tools from the toolbar
At the left end of the toolbar you can choose to Mirror on the horizontal/ vertical or both directions with the first 3 icons.
The 4th and 5th icons perform similarly, but you are able to set the number of rows and columns. You may also notice there is a setting to nominate the space between the rows and columns, you can also adjust these distances by dragging the mouse.
Icons 4 and 5 are the Array and Reflect tools, Array copies and pastes the object facing the same direction, while the Reflect tool flips each second object so they mirror or face each other.