${\mathrm{Ag}}_2\mathrm{O}+{\mathrm{H}}_2{\mathrm{O}}_2⟶2\mathrm{Ag}+{\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$
In an above reaction H₂O₂ acts as a/an

The reducing agent is the one that reduces the other substance and itself oxidized.

$\stackrel{+1}{{\mathrm{Ag}}_2\mathrm{O}}+\stackrel{-1}{{\mathrm{H}}_2{\mathrm{O}}_2}\to \stackrel{0}{2\mathrm{Ag}}+{\mathrm{H}}_2\mathrm{O}+\stackrel{0}{{\mathrm{O}}_2}$

H₂O₂ oxidizes from -1 to 0 and it reduces Ag from +1 to 0. Therefore, H₂O₂ acts as a reducing agent.