Looks like a mid-90's (1995?) entry level sport mountain bike. A bit better than a recreational mountain bike from that era.
You'll probably find the parts to be shimano STX or Deore LX, except the grip shift shifters(they were on everything for a couple years). The top model gripshift was srt 800; you'll probably find the ones on your bike to be in the 600 range.
Looks to be in good shape, and should make a descent errand bike with light trails; probably weighs around 28 to 30 pounds.
seatpost might be a 27.0 or 27.2
Welcome to the site; it's always fun finding someone else's discarded bike, and find it still has some use.