The minus sign for the period of rotation of Venus in tables indicates that Venus rotates in the opposite direction to most other planets in our solar system, including Earth.

Here's a breakdown:

* Most planets rotate counterclockwise when viewed from above the North Pole (prograde rotation).

* Venus rotates clockwise (retrograde rotation). This means that the sun rises in the west and sets in the east on Venus, which is the opposite of what we experience on Earth.

The minus sign is a convention used to clearly indicate this retrograde rotation. It's not a negative value in the traditional sense; it simply denotes the opposite direction of rotation.