Water in engine?

I know nothing about cars. I just got this 1995 Corsica from my grandmother for free. it has 39k miles on it. I just took it to get oil changed and they said there is water in the engine. What does this mean?

Not a good thing. I would assume that they found your oil had discolored, most likley whitish . Sure sign that you have either a blown head gasket(common on 4 cyl) or a cracked head. To sure, watch the oil to see if it is discolored, or if you are losing radiator fluid. If so, you will need to take it to a good garage that does major engine work. Would be well worth getting fixed regardless of what it is, but can cost 250-600 bucks depending on what you have to have done. Also what your local shops charge per hour. Some parts of the country charge more, some less. The worst case would be a cracked head, which is 200-400 bucks to replace(without labor) again, depending on what you have and local costs.