Brake Stuck
Sounds like a brake rebuild is about to happen. One of at least two problems are likely.
First, the caliper is seized, which often happens when a car is stored for an extended time, due to absorbed water in the brake fluid corroding the caliper bore and/or piston. The bad news is that both calipers are probably corroded a bit, as are possibly the rear wheel cylinders and the master cylinder. Might require the removal and reconditioning of all, and replacement of the brake fluid. At very least, remove the seized caliper and inspect the bore and piston. And of cource replace (and flush) the brake fluid.
Second possibility is the brake flex hose on that wheel has collapsed internally, which causes it to act like a check valve. I have heard of this but never actually experienced it myself. This requires that the hose be replaced (which might be a good idea in any event ) even if the outside of the hose doesn't appear to be cracked. This also applies to the flex hose for the rear axle.
There has been much discussion here on the merits of DOT 5 brake fluid (silicon based, no water absorption) versus standard DOT 3 and 4 (glycol based). No real consensus, except that they probably shouldn't be mixed, and that silicon-based fluid should probably only be used for brand new seal materials (NO old rubber parts). But DOT 3 fluid works fine in the real (non-racing) world, but MUST be flushed and replaced at least every 3 years, or more often in humid climates.
HTH