"Does anyone know what this is?"

Well sir I see Romex not enclosed in flex conduit. There's a foundation crack. There is a general mess left behind by whomever clobbered that hole in drywall. There's a waste drain with Studor vent ,cobwebs and dust. If you had turned the lights out before taking the picture there might be other stuff in there.

What needs fixed by a plumber? That weird pipe isn't using anymore and the plumbing seem to work fine.. The house is peer and beam - we dont have a foundation. It is an older home so i assume back then they didn't use the flex around the romex. Mice / rats have been getting in so i want to get this area fixed. i was considering using steel wool and spray foam around that hole in the wall. Thoughts on that?

Here is another picture.

It's remarkable what one can see when lights are turned on that were missed in the dark. What looked to be a foundation crack in the dark clearly became tile when light turned on.

Steel wool and foam should stop rats from getting through the hole.

Thanks. Is it safe to put wool and foam around that wire? I read the wool is a fire hazard.

"I read the wool is a fire hazard."

There's situation's in life when you shouldn't believe everything you read and trust common sense instead. If the truth is unclear in this case,try setting steel wool on fire.

You can actually set steel wool on fire with electrical current, or a 9v battery, so I am not sure I would use this close to wiring that rats or mice could chew on. I would expose the cracks and put in cement or cement with ground glass in it.

Our neighborhood was overrun with rats when they tore down a building and did something to the storm sewers at the same time. We plugged an entry to our walled yard with cement and a rat chewed through it before it was set. It was recommended to add broken glass to the mix.

Burning Iron in Steel Wool - Bing video

Thanks, I'm not sure what you mean by expose the cracks? It's a hole in the wall. I think I'm going to cut the breaker to the dishwasher tonight and plug the holes with steel wool - hoping they go out the way they came. Then I'll have a handy man come and properly patch the hole, then working on sealing any external points.

Expose the openings whatever they are and patch and fill them.

Thanks - patching is my plan but not with cement.

Fire block (typically red) foam could be used. You could embed steel wool in that, I suppose, but if I were to do that I would scrunch up stainless steel screening. Much tougher. Galvanized metal lathe is another material to consider.

Where does the cable go and come from?

it goes to the dishwasher.

If it is protected from damage in its normal configuration, such as behind the dishwasher, then I think you don't need to further protect it. This depends somewhat on whether moving the dishwasher could damage it. Certainly there is a limit to the number of times it can be flexed. I would suggest in general that it go to a box, perhaps just above the hole, and use a cord to power the dishwasher.

Thanks!

Basic cheap steel wool is going to rust. I would use something else like Kaseki suggested.

Thanks, I'm going to just have the sheetrock replaced imstead of filling up the hole.