Blood Elf racial abilities include:[2]

Mana Tap
Reduces target’s mana by 50 and charges you with Arcane energy for 10 min. This effect stacks up to 3 times. 30-second cooldown. Scales with level.
Arcane Torrent
Silence all enemies within 8 yards for 2 sec. In addition, you gain 10-161 Mana (10 Energy for Rogues) for each Mana Tap charge currently affecting you.
Arcane Affinity
Enchanting skill increased by 10.
Magic Resistance
All resistances increased by 5.

[edit] Classes
For more details on this topic, see Classes in World of Warcraft.
Blood elf characters can play as the following classes:

Hunter
Mage
Paladin (Blood Knight)
Priest
Rogue
Warlock
Though the Warrior class is available to all other races, the Blood Elves never received this, instead getting the Paladin class. Blizzard made this hard-to-decide change during internal testing The Burning Crusade. They chose to “balance out the draenei Shaman class, in exchange for a few other changes.”