Are you talking about that hole that looks like it was drilled into the drain pipe on the horizontal part? I can't imagine that's supposed to be there.

I'm hoping it is just the picture perspective, but that pipe should not run downhill like that. And no hole, either.

could you take a picture from further back, or landscape, to show the disposal attachment?

Looks like there may have been a drain line for something like an RO water system attached with a saddle clamp at some time in the past. That pipe needs to be repaired or replaced to stop the leak.

As a temporary measure, you could just put a couple of wraps of duct tape around it to cover the hole, since it's not under pressure. But it's just a few bucks to get a brand new replacement part and swap it for the one some bonehead drilled a hole in.