Refer to figures.
Sideslip Angle

It is becoming more common in the exams to ask about positive and negative sideslip angles. This kind of thing is mostly used by theoretical engineers designing and testing the aircraft, but all possible conditions of an aircraft can be described by a series of numbers. We are used to the numbers for things like pitch and roll angle, and of course, it is obvious that pitching up from the horizon should be considered "positive" and pitching below the horizon shall be "negative" pitch. As convention, roll is considered positive when it is to the right. Yaw is more complicated, if we yaw to the right (heading increasing), we consider that to be positive yaw, but the sideslip angle is more useful aerodynamically.

Sideslip angle (β) is the displacement angle of the airplane’s longitudinal axis from the relative airflow, when looking down at the aircraft, as shown in the figure.

If the relative airflow comes from the right of the aircraft, that means a positive sideslip (+β), and if the relative airflow is from the left of the aircraft, that is negative sideslip (-β).

Spiral Dive

A spiral dive occurs when an aircraft is very directionally stable (stable in yaw) and not very laterally stable (stable in roll). When a sideslip is induced, a stable aircraft will want to yaw towards the oncoming airflow direction, and in a balanced aircraft, would also roll away from the oncoming airflow direction. However, the aircraft's roll would not be as strong in this scenario, and the strong yawing effect may even overpower it due to the secondary effect of yaw being roll, which would cause the aircraft to yaw and roll towards the oncoming airflow.

An aircraft which may do this has the "spiral dive" mode of dynamic instability, and even though the aircraft is statically stable in yaw and stable in roll, it has this tendency for an unstable reaction (spiral dive) to occur if not corrected by the pilot. The good thing is that this is a slow process, it would be easy for a pilot to stop a spiral dive from occurring as the aircraft takes a while to start spiral diving.

Spiral dive is an aperiodic motion as it does not oscillate like dutch roll (which is its opposite), instead just happening in one direction, once, continuously getting further from equilibrium.

In this case, then, the aircraft is sideslipping to the right, so the strong yaw (and secondarily roll) will be to the right, and will overpower the smaller left roll force, causing a total right roll. This will be followed by more right sideslip, so greater right yaw and greater right roll, with the speed steadily increasing as the nose drops.