A strand is one individual metallic filament within a larger braided or twisted conductor. Because solid wires become too rigid and prone to fatigue at larger cross-sections, manufacturers bundle multiple strands together to create flexible power cables. The number, thickness, and lay direction of the strands determine the cable's flexibility, current-carrying capacity, and resistance to vibration.
Make sure you don't nick any individual strand when stripping the insulation off that 4/0 cable.
Related terms
Conductor
A physical material or wire designed to carry electric current with minimal resistance.
Cable core
The central current-carrying conductor and its immediate insulation within a larger cable.
Skin effect
Tendency of alternating current to crowd toward the surface of a conductor as frequency rises.