There are many hidden object puzzles throughout the game, and you must complete them to progress the story. They are different from normal gameplay in that objects are more hidden in the scene (as the name implies) and if you don't hit an item of interest it will count as a mistake. If you get too many mistakes in a row you will freeze for a while. For this achievement, all you have to do is complete one of the many puzzles, regardless of how long it takes or how many mistakes you get.
Here is a full 100% walkthrough; full credit goes to Average Achievement Hunter on YouTube: