Most light sources produce very messy and disorganized waves. Think of a standard light bulb in your bedroom. It spits out light waves in every possible direction at random times.
These waves crash into each other and spread out quickly. This is an example of very low spatial coherence. Lasers work in a completely different way.
A laser forces all the light waves to line up perfectly. The peaks and valleys of every wave march forward together. This organized marching is what chemists call high spatial coherence.
Because the waves are so organized, the beam does not spread out. It stays in a tight line over incredibly long distances. This property is crucial for chemistry tools like spectrometers.
A spectrometer uses light to figure out what chemicals are in a sample. High spatial coherence lets the instrument focus all the light onto a tiny target. If the light was messy, it would miss the small chemical sample entirely.
Students often think lasers are just very bright lights. The real magic of a laser is this perfect organization of the waves.