what is located under the battery on a 1995 ford escort

While not critical to anything on the car, there was a battery enclosure that uses that vent to channel cool air around the battery. It may also serve to channel Hydrogen gas generated by the battery away from heat sources. I lost mine on my '93 years ago and haven't suffered any ill effects but I do have a friend that had his battery burst the top off of it in his '93. It's always best to keep what the manufacturer put in place if you can.