Key
Squads
Characters
Key to the Codex Astartes

M Movement - Speed at which the unit moves
WS Weapon Skill - Hand to hand weapon ability
BS Ballistic Skill - Ability with ranged weapons
S Strength - Physical force
T Toughness - Resilience to damage
W Wounds - Amount of damage needed to die
I Initiative - Speed and agility in melee
A Attacks - Number of attacks per melee round
Ld Leadership - How brave the unit is

(To see the effect these statistics have on gameplay, see the Combat guide in the regular part of the web pages)