Pay phones are less common nowadays, compared to twenty years ago
There aren't as many pay phones compared to twenty years ago
Pay phones are less common nowadays, compared to twenty years ago＝２０年前と比べると公衆電話が減った
pay phone＝公衆電話
common＝よくある、ありふれた、並の
nowadays＝今日（こんにち）、最近
「〜比べると」は「compared to〜」です。例えば：
Compared to a sumo wrestler, I am pretty skinny＝私は相撲と比べると中々細い
There aren't as many pay phones compared to twenty years ago＝２０年前と比べると公衆電話はあまりない
アメリカ合衆国 
