A dipole doesn’t have a ground plane like some other antennas. A dipole is a balanced antenna and both sides work off of each other equally.

With that said, this one is probably used for receiving and if one end is connected to the electrical ground (different thing from antenna ground plane) then it’s going to be the left side with the uninsulated wire most likely.

Looks like the left is the shielding on the cable so probably ground.

The side with the ground wire (shield), so left side on the photo.