Font Family - Sets the font for the the current block if one is selected, otherwise for the cell where the cursor is at.
Font Size - Sets the point size for the current block if one is selected, otherwise for the cell where the cursor is at.
Cell Type - Cell types control how the cell is displayed. Please note that they have nothing to do with equation types (explained later).
Font Color - This sets the color for the current block if one is selected, otherwise for the cell where the cursor is at.