Just a quick rundown of what the various symbols on the abilities mean:
m - Mana: The number of 'm's indicates its mana cost. (A hero gets 1 mana per 3 intelligence, rounding up)
t - Tap: This indicates that the ability is used instead of a basic attack.
n - Non-combat: this can be used outside of combat.
x - Stackable: you may use this ability more than once per turn
i - Initiative: this ability affects the hero's initiative, and so must be used at the beginning of the turn, just after any ability cards
g - Global: this affects all locations; unless an ability has this symbol, it only affects the location that the hero is at
p - Passive: this indicates a passive component of an ability. If an ability has no active component, it does not need a 'p' indicator
r - Reaction: this ability is triggered by something else happening. It may be used out of turn sequence.
0 - No cost: this ability is free to use (once per turn)