An ability's target type determines what kinds of things can be affected by the Ability. Some of the most common ones are listed here.
Creature
Abilities with the Creature Target affect some sort of being. A "creature" doesn't necessarily have to be an animal, it may be an animated statue or a sentient plant. Check with your GM if in doubt of whether something is a creature or not.
Limb
Rather than hitting an entire creature, some Abilities will say that they only hit arms, legs, or limbs. If these Abilities are attacks, then they slightly harder to land a hit with than ones that can hit a creature anywhere. They require hitting that creature's AC + 2.
Vitals
Vitals Targeted Abilities need to hit a creature's head or other vital organs rather than landing anywhere. If these Abilities are attacks, then they require hitting a creature's AC + 3.
Item
Attacks that target items need different hit rolls depending on the type of item.
- Wielded items (such as weapons or shields): AC + 3 - BV
- Large worn items (such as armor or cloaks): AC
- Small searchable items (such as rings or amulets): AC + 6
If an ability that targets an item is successfully blocked, it automatically hits the item that blocked it.
Area
Abilities that Target an Area do not have a precisely defined size. Rather than affect a small, cohesive space such as a campsite, a room in a dungeon, or a small shack.These abilities may not have a Range specified.
Self
Self targeted abilities affect the creature that executes them. They may not have a range specified.
Ability
Instead of targeting some person, place, or other physical thing, some abilities target other abilities. These include cases that target attack target abilities, conjured spells, or other types of abilities.
Other
Some Ability Targets don't fit nearly into one of the aforementioned categories. In these cases, the Ability's Target will just say "Other".