You can see from this diagram that the two outer vertical fins (stabilizers) mounted on either side of the horizontal stabilizer near the tail rotor, are both clearly angled to starboard. Here is another angle of it from a BK 117

When the helicopter is facing straight on you can see the stabilizers are not. But when the stabilizers appear to be straight the helicopter is clearly at an angle.

The reason for this has to do with the tail rotor. In a hover and at low speeds the tail rotor is responsible for providing sideways thrust to prevent the helicopter from spinning uncontrollably due to torque. But when the helicopter accelerates into forward flight the stabilizers on the tail cause a weathervane effect and try to align themselves with the airflow.

By angling the stabilizers you can increase the force of this weathervaning. This aids the tail rotor in fighting the torque and ends up contributing so much that the tail rotor may not even be necessary at certain airspeeds and power settings. The tail rotor thrust can be greatly reduced and that power that would have been consumed by the tail rotor is now freed up to be used by the main rotor instead. This can allow for slightly higher speeds or more carrying capacity.

Several other helicopters take advantage of this and have it engineered into their design as well, like this Robinson R44