Mula means root. The star looks for the origin of a thing, the foundation under it, the cause nobody has found yet. Sometimes reaching that root means pulling up everything growing above it.
In Hindu mythology, Nirriti is the goddess of dissolution and disorder. She is not a comfortable deity and the tradition does not pretend otherwise. What she governs is the phase where something falls apart, and Mula is the star that goes looking at exactly that phase instead of turning away from it.
Its shakti (the special power a nakshatra carries) is uprooting. This should not be softened into a promise that every painful event is secretly good for you. Some things get pulled up and that is genuinely a loss.
Mula is known for research, investigation and asking questions other people find rude. Natives want the real explanation, not the polite one. Many of them end up in medicine, science, psychology or spiritual practice, all of which involve looking under the surface for a living.
A bundle of roots is the symbol, and roots do two things. They anchor a plant and they are the part you dig up when you want to know what went wrong. Mula holds both meanings, and reading only the destructive one loses half the star.