The 2 column layout is used to separate a row on an advanced page into two visible columns. Under the layout option, three setups are available.
The Split Layout option splits the row into two visible columns of even size, each of which span two columns worth of space.
The Left Large splits the row into two visible columns where the left column spans three columns and the right spans one.
And Right Large is simply the opposite of the Left Large. As with other situations, adding a widget will override what is in the rich text right above it.