Watercolor is Акварель in Russian.The word both means the watercolor paints and an actual watercolor painting. The word theoretically has a plural, but really it's mostly used in the singular.

Акваарель may come from the French word ‘aquarelle.’ Watercolor is a medium of art in the form of painting such as oil painting, charcoal, markers or colored pencils. One of the traits of watercolor is that it appears more transparent than marker or regular paint because it is “relatively pure with less fillers obscuring the color”. There are many different techniques for water-coloring from how you use the paints to how you lay them on the paper and what you do with the paper. Wet on Wet refers to the act of wetting the paper itself and then laying down the watercolor instead of working on a dry surface. Usually the surface used for water color has to be thicker to stand some of the rougher techniques used in watercolor.

As with many forms of art, watercolor can be used in therapy for patients as a way to express their selves if they feel they cannot with words alone, or a way to relieve stress in a positive way. For more information on watercolor such as its history or usage here is where I found most of my information: http://en.wikipedia.org/wiki/Watercolor_painting.