The squares represent the proportion of all words in the article. As there are 20 in total, each square is 5% of the total article. So as you have 2 green squares, 1 orange and the rest red it just means that you have 10% of the words in the article correct (green), 5% a close hit (orange) and 85% you haven’t got. Because you got the target quickly, most of the words in the article are still blank and so show as red squares.
When you guess a lot of filler words (is, the, and etc) you tend to get a lot more green squares.