On a standard inboad the drive shaft connectes to directly to the
engine and points out toward the stern of the boat. A V-Drive is
when an inboard engine is mounted such that it's drive shaft is
pointing toward the bow of the boat. Then a "V" type gear box
"redirects" that shaft so that it points to the stern.

Picture an engine in the aft and the
"V" rotated 90 degrees counter clockwise.