the ordered paired is (1, 20) represents the unit rate because for a unit rate it is the smallest rate. 1 minute is the smallest rate, meaning this person can type 20 words in 1 minute. If you want to know how long does this person take if they typed 600 words, you know that it takes 20 words for 1 minute.
this goes along with the second part. (3, 120) this person can type 120 words in 3 minutes. You see the 3 is on the x-axis and that says time in minutes. the 120 is the y value and on the graph it says words typed.