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