Haricot vert is what Americans refer to as a green bean. In French, haricot means beans and vert is the color green. It is also similar in looks and taste to a green bean.
Haricot vert are generally longer and thinner than the typical green bean in America. Another difference is that the flavor is slightly different, and they are more tender than the bean used in America. Green beans, snap beans and string beans are all adequate substitutes if haricot vert can not be found. The thinnest green bean is best to substitute for the haricot vert when using in a recipe or just steaming them by themselves.