It depends on the extent of the damage. If it's extensive, you may have to sand and refinish. If the veneer is lifted, you will have to reglue that first. If it's slight, like water rings, sometimes they can be fixed by rubbing a little mayonnaise into them.
HI Stan, here are some suggestions: https://www.rd.com/home/cleaning-organizing/how-to-remove-water-stains-from-wood/. I usually use a towel over the spot, then a hot iron (no steam) to try and dry it out. Hope this helps!
What is the furniture made out of?
Here's a post that might help - https://homeguides.sfgate.com/fix-wood-table-peeling-waterdamaged-top-38847.html
It depends on the extent of the damage. If it's extensive, you may have to sand and refinish. If the veneer is lifted, you will have to reglue that first. If it's slight, like water rings, sometimes they can be fixed by rubbing a little mayonnaise into them.