Percent funded
A reserve study compares what the association has saved with what it should have saved for future repairs. A low percentage means future repairs will likely be paid by special assessments or loans.
The next five years
Look at the repair schedule for big items due soon: roof, structure, balconies, elevators, plumbing, facade. Compare their cost with the money in reserves.
Is the board following it?
Compare the study's recommended yearly contribution with the budget. If the board has been contributing less, the gap is a future bill.
General information, not legal advice. Rules vary by state and by your governing documents.