Here is the full list of all 12 Resident Evil 4 achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Clear the game on the highest difficulty.
Acquire all of the costumes in the game.
Summon the master of the lake. Don't rock the boat.
Defeat Saddler in battle, and escape from the nightmare.
Defeat Krauser, your former partner, in battle.
Acquire all of the bottle caps in the game.
Defeat Salazar, and make your escape from the castle.
Turn the tables on Verdugo, the right hand of Salazar.
Defeat the village chief in battle.
Outmaneuver the rampaging beast, El Gigante.
Rescue the president's daughter, Ashley. Afterwards, the real fun begins.
Ring the mysterious bell. What happens after that, is up to you.