Scotland does not have an independent grid. There is an EU wide market to trade electric energy between countries. Some days they export elecric energy, other days they import it. Even if 100% of their local production is renewable, the energy they import is probably (partly) not. So I guess the 'equivalent' means that summed up over the entire year, they export at least the same amount of energy that they import.

You can check this site for the present state (it doesn't show scotland though): https://www.electricitymap.org/