For every oxidation there is a reduction; and for every reduction there is an oxidation.
Sodium is oxidized; iron is reduced.
Carbon is oxidized; oxygen is reduced.
Oxygen is reduced, sulfur is oxidized.
Dihydrogen is oxidized; oxygen is reduced.
Copper is oxidized; silver is reduced.
All the oxidations feature an increase in oxidation state of the species that is oxidized. Likewise, all reductions feature a decrease in oxidation number of the species that is reduced. You might want to look up the method of half equations for the balancing of redox reactions.