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