What is this? It was outside for a while, but that's not the concern. What plant is this? And should it better rest here or bad for the Jade plant?
Take it out and pot it up separately if you don't recognise it but you want to see how it grows - generally, plants that germinate on their own in soil outdoors (in pots or not) are usually plants you don't want, or weeds, and it will be more difficult to get rid of it later without disturbing the roots of the Jade plant. I don't recognise the seedling I'm afraid.