Trois crayons is a fancy French way of saying "three pencils". It's a special technique that artists use to create really pretty drawings. Instead of using just one pencil with one color, trois crayons artists use three pencils - one red, one blue, and one black.
The red pencil is used to make warm colors like orange and pink, the blue makes cool colors like green and purple, and the black makes dark shadows and outlines. The artist starts by lightly sketching the basic shape of what they want to draw with the red pencil, then they add the blue to give it some depth and shading, and finally they use the black to make it really pop and stand out.
The cool thing about trois crayons is that it gives the drawing a soft, almost dreamy look. It's like looking at a beautiful painting, but on paper with just pencils. It takes a lot of practice and patience to master trois crayons, but it's definitely worth it if you want to create something really special and unique.