Why for this life there's no man smart enough, life's too short for learning every trick and bluff.
There are various types of symbols on skills and cards.
A (action - only in Lost Legion): your one and only action for a regular turn. + (special): any time. hand (heal): not during combat. head/crossed swords/foot: Cannot be played in a rest turn (a turn in which you forfeit your move and action).
In the basic set, the head corresponds to influence, the swords combat, and the foot movement, but Lost Legion rules do away with this distinction. Basically you can play and power them whenever there is a reason for doing so (in a regular turn). Even if you don't have Lost Legion this update to the rules is recommended for simplicity and clarity.