When used alone, it means to display all contents of a cell array.
C = {magic(3);'how';rand(1,2);'pizzaz';magic(8)};
C{:}
When passed to a function, it will form a comma-separated list. For example:
C = {magic(3);magic(2)}
isequal(C{:}) % This is the same as isequal(C{1},C{2})
Now change it to:
C = {magic(3);magic(3)}
isequal(C{:}) % This is the same as isequal(C{1},C{2})
