Oxidation numbers vary from -7 to +7

LEFT TO RIGHT – OXIDATION
If the oxidation number of an element moves from left to right in the scale:
THE ELEMENT IS OXIDIZING and it acts as a REDUCING AGENT

In the reaction Involving Iron(II) ions (Fe2+) and producing Iron (III) ions (Fe3+), the oxidation of Fe changes from +2 to +3
Fe 2+ → Fe 3+
The oxidation number in the scale moves from left to right, so Iron is oxidizing, and of course, it acts as a reducing agent
RIGHT TO LEFT – REDUCTION
If the oxidation number of an element moves from right to left in the scale:
THE ELEMENT IS REDUCING and it acts as an OXIDIZING AGENT

In the reaction Involving Manganate (VII) ions (MnO4–) and producing Manganese (II) ions (Mn2+), the oxidation of Mn changes from +7 to +2
MnO4– → Mn 2+
The oxidation number in the scale moves from right to left, so Manganate (VII) or Manganese VII reduces, being in this case an oxidizing agent