Print heading rows or columns on every page

Choose File → Page Setup.
Select the Sheet tab.
Click in the Columns to Repeat text box (or Rows to Repeat).
If you can’t see the column or row headings (the numbers or letters), drag the dialog box out of the way (drag its title bar).
Select the column(s) (or rows(s)) you want to repeat on the left side of every page. Click to select one column (row) or drag to select multiple columns (rows).