As the name implies, the Archer is a strictly ranged ombatant, boasting some of the best versatile mobility in the game.
Being an Archer gives you the unique ability to climb trees. This can be incredibly useful to simply gain height for taking pot-shots or evading pursuers & melee combat. It is however, best to not be relied upon as both enemy knights and builders can chop trees down.
Your only weapon of offense is the bow and arrow. It is, like the knight's sword, a charge-up weapon that goes further and faster while also doing more damage the longer you charge up. The charge-up is symbolized by the circle that forms around your cursor when using (M1)
When spikes form on the circle around your cursor, your bow is at It's absolute maximum. The moment this happens, the game will allow you to fire three fully charged arrows in a very quick succession. It is currently the only method of breaking down a Knight's shield temporary as an Archer.
The utility item you will also exclusively receive as an Archer is the hook-shot. It is as the name suggests, a hook that you shoot out away from your character to attach to a solid surface. It has a relatively long distance and can be extremely useful for scaling enemy fortifications. It's used with the (M2) key.
The Archer's main goal is usually to annoy and harass the enemy while being untouchable or make quick dashes to grab the enemy flag and then re-scale fortifications to get it back to your base. Both roles require finesse and plenty of game-knowledge so practice is normal before any remote numbers of success are achieved.