Home Improvement

For context, this is leading to my AC unit. While hanging a light above my workbench, I noticed daylight coming in from the wall where there shouldn't be any. It appears a previous owner had pulled back the insulation and forgot to put it back - shudder to think how much money that's costed me over the last two years. Would like a hardier seal than insulation to stop water and mice, but not sure what is required.