By the term image 'noise' we mean a bit on the 'grainy' side, particularly in the shadows. This often happens when a high Iso is used. I like to keep my Iso as low as possible and rarely go above 800; although it is possible to use much higher settings when shooting in good light and the increase is to obtain faster shutter speeds etc.
Your shot has come out well for 1600 Iso and the 'noise' or 'grain' like faint very small speckling in the shadow areas is only just noticeable.
I often get a lot of problems with noise in the shadows of my high contrast shots; which is made worse when some under exposure is used to prevent highlights over exposing. But some people tend to deliberately produce images which have a lot of very noticeable noise as a main item of the scene.
There are noise reduction options in many editing programmes but using these methods tends to also reduce image sharpness when used to excess. Sometimes, I will create a selection around my main subject area and only sharpen that area; then reverse the selection and only apply noise reduction to the unimportant background areas. However, we are getting into specialist use territory now.