Hello there! This is a tutorial that will show you exactly what the Add Cube tool does. It is an additon Blender published with the Update of Blender 2.92.0, so if you haven't updated, here's how!
Update Tutorial:
• How to Update Blender | For Abolute Beginners
Modeling Tutorial (includes Mirror Tool):
• How to Model a Character in Blender 2.9 | ...