As is, the equation has:
Reactants:
2 K
2 O
2 H
Products:
1 K
1 O
1 H
So, we can add coefficients to balance the equation:
K2O + H2O = 2KOH
The coefficient means that there are 2 moles of KOH, and now the equation is balanced as there is 2 of everything on both sides.
