It is a visual test used to estimate abstract reasoning. The patterns are often between 2x2 and 6x6 matrices of symbols. One of these symbols is usually left blank and supposed to be deduced from the others.
The overall concept is very similar to the Abstraction and Reasoning Corpus but is much more tied to human vision. This makes the range of possible tasks much larger but also harder to integrate in an algorithm. You already need a powerful computer vision system that can convert the matrix into a usable representation before you even try to implement reasoning.