Balance means that you just have to have ...similar sized items in your artwork. When items are exactly the same...we call that "symmetry"
Here is an example of symmetry. Can you explain why this is so?
if you said...."it is symmetrical because the pillows and lamp stands are the ...exact same on each side" you would be right!!
The picture up above is centered ....or we can say balanced in the middle! note....the words ..."rent cafe" were part of this artwork...by them being there....this basically unbalances the work. so, what would you add to change this?