Its a weed if you don't want it there. But it isn't any species of wild plant from your area. Just another succulent. They grow easily from bits which break off. So this is probably a piece which just fell off a neighbour. You could pot it up separately and see whether you want to keep it.

Sedeveria was suggested on NTP.

After looking again on a bigger screen, the foliage may be pairs of opposite leaves, which would negate Sedeveria. I agree with the leaf-from-another-plant-fell-in-the-pot theory, but doubt my original suggestion @ this point.

What is this plant looking like now?