In the sense you're thinking of it literally means "Следи за собой" but you wouldn't use it in this context. If someone falls down or something like this where in Russian you can say like "Тихо тихо!!!" In English you could say either "watch out" or "be careful". Lampada is correct as it also is a way of saying goodbye. Basically, take care of yourself, something like всего хорошего, but not as formal.