I received some gear and I don't know nor understand the symbols beside there icons. Or is the level of the item preventing me from equipping it to my character of a lower level?
Item levels do not matter at all. However, many items require Talents to equip. Clear (white) Circle talents and Bronze Square talents are the ones you will be dealing with in the Beta. Your characters unlock talents as they level up. Before you have them, or if you don't have enough, you can't equip items that require them.