2Li + __H₂0 = __LiOH+H₂

balance the equation

2Li+2H2O=2LiOH+H2

We need to make number of the atoms of each reactant (the elements from the left side) equaled to the products (the elements from the right side)

Li is 2 on the left side so in order to make it balanced we add a 2 in front of LiOH.

For the H2O we take a look at the right side there are 2 atoms from H2 and 2 atoms of H for 2LiOH therefore we have 4 atoms of H in the right side and only 2 in the left side. So, to make them equal we will add a 2 in front of H2O.

Hope, I explained well.