In a chemical name, the cation is always named first, followed by the anion.
So, hydrogen is the cation here and oxide is the anion. The chemical symbol for hydrogen ion is $$H^+$$, and that for oxide ion is $$O^{2-}$$.
Now, to balance the $$-2$$ charge of oxide ion, we need two $$H^+$$ ions $$(H^+,H^+)$$. Combining the cation and the anion, we get the chemical formula as $$H_2O$$. The signs of charges are always ignored while writing a chemical formula.
Therefore, the chemical formula for hydrogen oxide is $$H_2O$$.