It means it lacks value or interest. Un valuable. Nimio, insignificant, trivial, puerile, ballad, futile, frivolous. It can also mean ordinary, ordinary, vulgar.
A dull person is one that lacks grace or interest. The bland adjective is used to define people or things insignificant, ineffective or insubstantial. In medicine it is used to indicate that it does not cause pain.
It is the person who does not care about nothing, leaves that all others to solve it