This is somewhat misleading - it appears to be offsetting energy exported when there's particularly good conditions for renewables against times when there's not. In reality they are still both burning some fossil fuels and importing energy from countries that are burning fossil fuels. What really should matter is the carbon intensity of both electricity production and consumption.

In terms of hard numbers for Scotland, their carbon intensity is 59 gCO2/KWh (https://www.carbonintensity.org.uk/), which is actually pretty great. You can compare against other countries here - https://www.electricitymap.org. Here's the current breakdown of their electricity production:

Wind: 36.5%

Nuclear: 31.1%

Hydro: 16.7%

Gas: 13.5%

Biomass: 1.4%

So right now they are 52.2% renewable energy. Presuming they are running renewables to capacity, this low carbon intensity figure is actually being kept low due to the fact they are sourcing a third of their load from nuclear. Should the Scottish government phase out nuclear as they are currently planning (https://www.gov.scot/policies/nuclear-energy/), then we can expect this carbon intensity to rise as gas is used to pick up the base load when conditions for renewables aren't favourable.