Aircraft and Vehicles are supposed to represent a single unit, while officially soldiers represent “several men,” which of course leads it wide open to interpretation.
My view is that for regular infantry it represents a Half-Squad or Fire Team. For support units such as the Bazooka, Panzerfaust, etc, it represents roughly two teams. Commanders are the commander plus staff, which could be largely non-combatant such as with the SS-Hauptsturmfurher or a command squad using more regular soldiers such as the Red Devil Captain.
I’m also fairly sure that artillery pieces such as the Anti-Tank Guns represent one unit. As for the Light Mortars it’s likely a battery of them, though the Japanese one seems more equivalent to a full squad (which is actually how the Japanese fielded them in Rifle Companies).