Style can have a few meanings when you’re talking about storyboards. It can refer to your particular style of drawing. For instance, two comic book artists may each have very different looks. Some board artists’ drawings are cartoony and some are more realistic.
Style can also mean technique. Everyone has his or her own style and favorite techniques for drawing storyboards. Some artists prefer pencil, as I do; others use pen and ink or gray-tone markers; and others may prefer full color or handling all the illustrations digitally.