Editable vectors out, not a flat picture.
Export copies a clean, self-contained SVG to your clipboard. Paste it into Figma and you get grouped, editable vector layers. Sketch, Illustrator, Penpot and Framer all behave the same way.
The dropdown will also write you SVG and PNG files, and a GIF whenever the design has a timeline on it.
Why SVG rather than PNG? An SVG is small, scales to any size without going soft, and stays editable afterwards. A PNG is a grid of coloured squares. Fine as a finished image, no use at all if you want to keep working.
Is there a watermark? No. What you export is yours.
How big can a design get? There is a shape budget, so the browser stays usable. Dense systems thin themselves out gracefully instead of locking up the tab.