What do the red, yellow and green skill signals mean?
Short answer
They show how much evidence backs a skill: green means confirmed from real work, yellow means declared or partly supported, and red means stated but not yet evidenced.
The colour is an honesty signal, not a grade of how good you are. Green marks a skill a manager has confirmed from work you actually did; yellow marks a skill you have declared or that has some supporting activity; red marks a skill you have listed but for which there is no evidence yet.
The point is to keep self-stated and evidenced skills visibly separate, so both you and an employer can tell what is proven. A red signal is not a criticism — it simply shows where confirmation could be added next.