A PNG is a grid of measured colours. An SVG is a list of instructions: draw a circle here, fill this path, set that stroke to two units. The first is a recording; the second is a score. Converting between them in one direction is trivial and in the other is essentially impossible.
SVG to PNG: easy
Follow the instructions at whatever size you like and record the result. Because the instructions carry no resolution of their own, you pick one at conversion time, and you can pick again tomorrow at four times the size with no loss.
PNG to SVG: not really
Going the other way means looking at a finished drawing and inferring the instructions that produced it, which for a photograph is not a well-posed question. What our converter does — honestly labelled — is wrap the image in SVG packaging. The file is valid and it will open, but the pixels are still pixels and enlarging it still blurs.
Worth knowing
Tracing tools exist and do genuinely convert simple flat graphics into real paths. They work well on a two-colour logo and produce expensive nonsense on a photograph of a face.
What people actually want
Usually one of two things: a logo that stays sharp when enlarged, which needs the original vector file from whoever designed it, or a smaller file for a website, which needs WebP. Neither is solved by converting a PNG to SVG, and we would rather say so on the tool page than take the conversion and let you find out.