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