Elemental Attacks or Spells are anything that deal elemental damage. Elemental Damage can be any one of four types:
The Elementalist class specializes in dealing damage using skills from one of the four areas. Most wands, staves, and canes also deal elemental damage. Weapon Upgrades can cause a normal weapon to deal elemental damage.
Many armor sets in Guild Wars provide increased protection against a certain element. For instance, the Pyromancer's Armor gives the wearer an extra +10 Armor against fire damage and +10 Armor against elemental damage. Normally, the wearer of such armor would have 60 AL per piece against an attack directed at him or her. However, if that attack was fire based, then the wearer would have 80 AL per piece against that damage source.