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