Question

How to balance barium and oxygen yield barium oxide

Answer 1

Barium : $Ba^{+2}$ with +2 being the charge
Oxygen : $O^{-2}$ with -2 being the charge

The given equation can be written as:
Ba + O = BaO

Since the sum charges of Barium and Oxygen equals 0, there is no need to add subscripts.

Both Ba and O appear on the left and right side of the equation once, so there is no need to add a coefficient.

Ba + O = BaO is balanced