On this map, there are 4 ways to get a "folder" ( black icon) and getting one blocks the number on your action strength.
This means if you have two of them, you cards at position 1 and 2 already count as strength 3.
The other two spots are on the 4 and 5.
If you have all 4 icons covered you can do an action card at spot 4 and it counts as strength 6 for instance.