The subtype of a card is the first line of text under the picture and to the right of the hyphen. subtypes may be Creature type, Planeswalker type, instant/socery type (arcane) or a variety of other of other types. For example, Cat, Goblin, Bird, and Elf are creature subtypes. Ajani and Jace are planeswalker subtypes. Equipment, Aura, Trap, Arcane, are more subtypes.
Please note: these are only the "main" subtypes. there are hundreds of creature subtypes in existence. This will not list all of them.