Anything hypoallergenic is unlikely to make you sneeze, wheeze, or break out in hives. In other words, it probably won't send your immune system into overdrive.
When something is hypoallergenic, it's unlikely to cause an allergic reaction. Hypoallergenic cosmetics most likely won't make your skin break out in an itchy rash, and hypoallergenic dogs are your best bet if you want to convince your allergic dad to let you bring a puppy home. Keep in mind, though, that hypo- means "less," not "none" — it’s entirely possible that your adorable, hypoallergenic labradoodle will still make your dad sneeze.