Families are like mini-guilds. You get your own family chat and can share land between family members. You can even have cross faction toons in your family (including pirate and player nations), though you won’t understand the other continent’s language just by being in the same family.
Family dailies are your main source of vocation. You MUST have another family member nearby for one of them. Family members also get a bonus to vocational exp and other minor bonuses when the family levels up.
You can get up to 4500 vocation through family dailies plus 20 Onyx Archeum Essence (an essential crafting resource) through the trade run daily. Buy a cargo pack from a trader and run it across the water to either Two Crowns or Solis. If you don’t have a clipper to sail on, this is a safe run if you purchase a Captains Protection item and take the NPC ferry between the two zones.