Numbers allows you add comments to specific cells. Comments appear in small yellow boxes that resemble cartoon speech bubbles. Adding comments is as simple as selecting a cell and then clicking the toolbar’s Comment button. You edit comments by clicking in the comment.
You can hide all comments by selecting Hide Comments from the View menu (cells with comments will have a yellow mark added to them that, when clicked, will display the comment). You can hide and delete individual comments by clicking "-" or "x" in the comment, respectively. Visible comments appear when printing.