Tooltips display documentation on functions you are attempting to use in the cell input area. To see an example of this, type print() in the input area and place your mouse in-between the parentheses.

Next, hit the Shift and Tab keys. You will see a window that contains information on the print() command in Python, as shown in the following screenshot:

This information is the standard Python documentation about the print() function, which shows the arguments and their values.