Okay kiddo, so the g factor (short for "general intelligence factor") is like a special power that some people have. It's sort of like being a superhero, but instead of flying or shooting webs, these smart people are really good at thinking and problem-solving.
Think of your brain like a toolbox, and these smart people have a really good all-purpose tool in there that helps them figure things out. We call that tool the "g factor." It's like a super-smart little robot inside their heads that helps them do things like puzzle-solving, math, and coming up with creative ideas.
Now, not everyone has the same amount of g factor. Just like some superheroes are stronger or faster than others, some people have more of this special brain power than others. And just like how superheroes can train their bodies to get stronger, people can work on training their brains to increase their g factor too.
Scientists study the g factor to try and figure out what makes some people naturally smarter than others, and how we can help everyone work on increasing their brain power. It's like trying to figure out the secrets to being a superhero, but for our brains instead of our bodies!