Well, sweetie, entering heaven alive means going up to heaven without dying first. You know how when we get old or really sick, our bodies stop working and we have to leave this world to go to heaven? Well, some special people in history were so good and kind that they were able to go up to heaven without their bodies giving up on them. It's like when you do a really amazing job on something and your teacher gives you a special award for your hard work. These special people are given a reward by God to go straight to heaven without having to die first. It's kind of like a special, very rare treat just for the best of the best. Does that make sense, sweetie?