I just got my very first real camera which is a Nikon D3500 and I am so incredibly excited to start taking better photos of my family especially with my daughters 3rd birthday coming up in a few weeks. Right now I only have the lens that came in the box but I keep hearing I need a prime lens for those blurry backgrounds everyone likes because it looks so professional.

I honestly have no idea what that even means or which one fits my camera since there are so many numbers and it is all kinda confusing to me. My budget is around $250 max for now. Sorry if this is a dumb question but which prime lens is actually the best one for portraits?