Signs somehow cause a bridge to be formed between the realm of spirit and the realm of form. This can also be explained as a light bulb moment or a deeper feeling/understanding of something.
A sign is an abstract symbol, connecting to the sub/UN-consciousness, that then moves into your conscious mind/world. Here it becomes a messenger of important information about your present or even future circumstances, also acting as a reflection, which may help you to understand your self or actions from a different perception.
Image by Toni Carmine Salerno