So from the information, we know that Anne is a carrier so her genetic makeup is XBXb [B for normal and b for colourblind] hence she is an open circle which denotes unaffected female. It says Mari's father John is unaffected therefore, his makeup must be XBY, Y cannot carry anything [hence why males cannot be carriers].
Okay for the pedigree now we move on the second row, we now make 3 squares each denoting 3 of Maria's brothers, colour 2 in because the info says 2 of them are affected, leave one open for the unaffected one.
Ok next to Maria, if we do a simple punnet square from Maria's parent you get 2 possible genetic makeup for Maria, she is either XBXB or XBXb, either way she is not colour blind because for colour blind u will need XbXb which is impossible since Maria's father is XBY. So Maria will be an open circle. Given no information of Nick he is an unknown square denoted by the question mark and at this point we are unsure of Maria's son given the question mark as well.
That completes the pedigree.
Edit: Zoom in to see the writing on attached picture sorry it's a little messy using paint.
