If you say you've been blessed, you feel lucky to have something: health, love, fame, fortune, talent, etc. I'm very happy for you; the only time I feel blessed is when I sneeze.
You can pronounce blessed as one syllable (“blest”) or as two (“bless-id”). The phrase “blessed event” is an old-fashioned way of referring to a baby's birth. If you've been blessed with musical talent, you might pick up the piano quickly. If you've been blessed with physical strength, you should still pick up the piano carefully.