Coloring here means an activity that kids do. Like what they are doing if they want to color something. It is not like what we meant for food coloring idea.

Coloring (American spelling) or colouring (British/Canadian spelling) is an activity most often enjoyed by small kids. They use crayons, coloured pencils or markers to colour in an outline of a picture and turn it into a work of art! You can buy a "colouring book", a soft-covered book with black outlines of pictures, for your little ones to practise their fine motor skills through colouring. Colouring is a great activity for kids, and it is very easy to bring a colouring book and crayons with you to occupy your child when waiting for an appointment.

Filling in a shapes with color using crayons, typically in a coloring book.