Hello Ezzat.
''mouldy'' means covered with ''mould'' (a green or grey growth that develops on old food or on objects that have been left for too long in warm, wet air), for example ''mouldy bread / mouldy cheese''.
"mouldy'' can also mean in an old-fashioned way ''unpleasant / of little value / not modern'', for example:
All he gave me was a mouldy old 50p.
The city's museums are filled with mouldy old collections.
I hope this helps :)