Armour is the equipment you wear that provides the stats used to calculate how much damage is dealt or taken.
Understanding the tooltip
Picture -- generally helpful as to type of equipment
Name -- often helps categorize the piece as offensive or defensive
- color of text tells the “color”, of the piece
- yellow text < purple text < teal text < gold text
- account: can trade or to alts on the same account
- Character: no trading
- Bind (to character or account) on equip: free to trade until put into an equipment slot
- Bind (to character or account) on acquire: the binding happens when it's removed from the chest
- Fellowship tradeable (timer): Can be traded to a fellow or raid member who was present when chest was made, and did not have chest locks on; afterwards will bind to account
Heavy/Medium/Light armour -- affects who can use it; generally indicated amount of armour, if applicable, and type of stats (main stats) found on it
Essence slots -- empty slots for putting essences in
Armour value -- 100% to physical mits, 20% to tactical mits
Other stats -- stats intrinsic to the piece, unchangeable; tend to be categorizable as offensive of defensive, and correlate to the names.
Durability -- damage taken, and left ‘til it needs repaired
Minimum level -- character must be this level to equip the item
Worth -- value if you sell it to a vendor
At level 120, there are several sets of full gear available when you're ready to upgrade beyond the quest-rewards you earn in the Grey Mountains. Each set generally has 2 options for each piece of gear -- 1 is offensive (DPS & support), 1 is defensive (tanks & healers). Below is a table to give you an idea where to start looking for the next level of gear for your toon.