Antibody tests look for evidence of the immune response to covid-19. The aim to answer the question: have I been exposed to COVID-19 and produced an immune response? You can read in more detail about the types of test here. If you want to see if you are carrying covid-19 now, you need to use an antigen test (PCR test).
We do not yet know if the antibodies are protective to make you immune and we do not yet know how long this immunity will last.