The Stableford System is a scoring method in which golfers earn points based on their scores in relation to par on each hole. The Stableford System is a good scoring method for recreational players because there are no negative points - a double-bogey or worse is worth zero, but everything else earns you points. (This is different from Modified Stableford, used on some pro tours, in which negative points do come into play).
To mark Stableford on a scorecard, it's most common to use two rows. Using two rows makes the scorecard easier to mark and easier to read later.
The top row is your stroke play score - the number of strokes you took to complete the hole. The second row is the Stableford points earned on that hole. At the end of each nine, tally up your Stableford points, and at the end of 18, add your two nines together for your final Stableford score.