Russia outside SWIFT: What does this sanction mean that would paralyzing the Russian state in case it was established?

Western states, led by the United States of America, Great Britain, the EU, have imposed a series of strict sanctions on Russia.

One of the measures that can be taken and the largest possible is Russia's expulsion from the World Banking System SWIFT.

This would make almost as difficult as paralysing the work of Russia's banks, obviously implying economic costs even for Western states whose banks are related to Russia.

Such a measure is mentioned mainly in analytical circles, but it may be the last to be placed in Russia. /Periscopi