A high power Burning laser can burn things because the beam is extremely concentrated light and light energy can be absorbed by some objects and converted to heat.
The burning ability of a laser depends on several factors.
Laser Output Power: Higher power laser beams burn things more easily and faster.
Laser Beam Width: A thinner laser beam always burn things better than a wider laser beam.
Object Color: Dark colored objects normally absorb more light energy so they are easier to burn than light colored objects that sometimes do not absorb light energy.
Immobile: A moving laser beam does not give the object enough time to absorb light energy. The laser beam dot needs to keep still on the object for several seconds to make it burn.