Here is the full list of all 38 Dark Souls II achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Earn all achievements
Learn all miracles
Learn all pyromancies
Learn all hexes
Inherit Benhart of Jugo's equipment
Learn all sorceries
Inherit equipment from Lucatiel of Mirrah
Increase the population of Majula
Inherit equipment from the head of Vengarl
Inherit Steady Hand McDuff's equipment
Discover the covenant of the fittest
Discover the covenant of rodents
Light all flames on the map in Majula
See the ending
Inherit Laddersmith Gilligan's equipment
Discover the covenant of the bloodthirsty
Discover an ancient covenant
Defeat Vendrick
Discover the abysmal covenant
Learn all gestures
Inherit Captain Drummond's equipment
Acquire Ashen Mist Heart
Max-out devotion to covenant
Acquire the King's Ring
Reinforce a weapon to its limit
Defeat Looking Glass Knight
Light the primal bonfire in the Black Gulch
Light the primal bonfire in Brightstone Cove Tseldora
Discover the clangorous covenant
Light the primal bonfire in the Iron Keep
Give Rosabeth of Melfia something to wear
Light the primal bonfire in Sinner's Rise
Discover a most brilliant covenant
Discover the covenant of the protectors
Discover the covenant of the meek
Defeat the Last Giant
Die for the first time
Reclaim flesh and set out as an Undead