When you look at the picture, for example the twig/branch to the left you will see lots of blocks of colour that are just a bit random, the colours are not uniform. This is the noise referred to. It generally indicates you used a high iso (i.e. 3200 or higher) to get the correct exposure. A high iso is required if you have little light or and/or need a faster shutter speed but is normally fixed by some use of flash/fill light (hence all the thread on lighting on the forum). Its always best to start as low as possible, i.e. ISO100 and work from there.