Attack is a value found on weapons and characters as well as traits. Attack and defense directly influence turn power during combat. For more information the exact manner in which Attack influences combat, see the mechanics article.
Players gain bonus attack based on their level. The amount is equal to the player's level divided by three, rounded down. That is, at third level, the player has one bonus attack, and a sixth level player will have two bonus attack. This appears as a green "+#" entry on the set-up description on the Camp page following the Attack Power of the weapon currently equipped.