Sensitivity refers to the ability of the test to detect persons with SARS-CoV-2 antibodies. It is called the true positive rate. Most people who have antibodies will be identified as highly sensitive tests. Very few people are unlikely to get a false negative.
The ability to identify people who don't have antibodies is specificity. It is also referred to as a true negative rate. It is a highly reliable and specific test that hardly produces a false negative. This means that its accuracy levels are pretty high.