Strength

Strength is part of the main stats, also called SPECIAL-Co values.

In these rules it's usually abbreviated with a single "S".

Pure, primitive bodily strength. Strength influences, among other things, how far your character can throw things, how well they do in close combat, how much damage they do unarmed, how much they can carry and how well they use bigger and really big guns.
Strength is therefore the most important stat.