It is difficult to say definitively whether or not they can foreclose on your property without knowing the details of your homeowner's association agreement. In most cases, delinquency is grounds for a lien on the property. Paying off the balance in full with interest will give you the right to have the lien lifted. Be careful, you shouldn't sign any documents that limit your rights. Instead you should send them back a letter with your first payment. In the letter you should make it clear that you are not consenting to any additional obligations and that you are prepared to pay off your delinquent dues and late fees only. If you can afford to pay off the entire amount at one time, I would recommend that and make sure to note on your check "payment in full". Good Luck
In California, HOAs are governed by the Davis-Stirling Common Interest Development Act.
Associations are allowed to record a lien but may not start foreclosure until the delinquent assessment is at least $1,800 or the delinquency is at least 12 months old pursuant to California Civil Code §1367.4(b)(2).
Most probably (and commonly) when you bought a condominium, like it or not, you agreed to be a member of a homeowners' assocation and to be bound by the terms of the CC&R which most probably contains clauses which allow the HOA to put a lien on your property if you fail to pay your assessment (even once). And yes, most probably, they are allowed to impose late fees and interests and the cost including attorney's fees to commence a nonjudicial foreclosure against the property should they choose to got that route.
In addition, you should know that in Calfornia, an HOA debt is a personal debt which means they can come after you personally.