The boy has just lowered his pipe and looks with satisfaction at the bubbles he has sent flying.
One hand holds the soap dish, a scallop shell which still holds a few trembling bubbles. The boy is balanced on a giant soap bubble, surfing the waves on an equally giant shell.
This vessel constitutes a surreal element within what is otherwise a realistic depiction, proclaiming the motif to be an allegory.
The motif is a "memento mori", a reminder of the transience of happiness and the brevity of human life. The work combines two well-known tropes from the 17th century: Fortuna, the goddess of good fortune, rolling on the waves on a ball, and the "Homo Bulla (est)" ("Man is a bubble") concept, which is often portrayed as a child blowing soap bubbles. (http://www.smk.dk/en/explore-the-art/highlights/karel-dujardin-boy-blowing-soap-bubbles/)