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