A monster will ALWAYS make ranged attacks if there is a value next to their ranged icon on their statistic card.
A monster’s range value is the base number of hexes away from the monster’s own hex that the monster can reach with an attack or a heal.
If the focus character is not in range after the monster moves, then the monster cannot attack that character.
Monsters must have Line of Site in order to attack their focused character, if they do not, they cannot attack.
A “–” as the range value signifies the monster’s normal Attack action can only target adjacent hexes (i.e., a melee attack).
Sometimes monsters with a melee icon on their statistic sheet will make a ranged attack, IF one of their ability cards shows a ranged icon, these monsters will then follow normal ranged attack rules.
Any ranged attack targeting an adjacent enemy gains Disadvantage against that target.
Draw 2 attack modifier cards and choose the worse one to resolve.
A monster adjacent to a focused enemy will move away from it until it can perform the ranged attack without Disadvantage (usually this will be just one space).
This archer would move one space away before making its ranged attack.