Given the equation representing a reaction: sn4 + (aq) + 2e - → sn2 + (aq) which term best describes this reaction?

Answer is: this is reduction.

Reduction half reaction: Sn⁴⁺ (aq) + 2e⁻ → Sn²⁺ (aq).

Reduction is lowering of oxidation number because ions or element gain electrons and oxidation number is decreased (in this example from + 4 to + 2).

In oxido-reduction reaction, at least one element lose and one element gain electrons.

Oxidation reaction is increasing of oxidation number of atom, because element lost electrons in chemical reaction.