Every time I listen to it I understand it says "you CAN stop the clocks". So for me, I believe this song is about being with someone who absentmindedly stops the time for both of you. Someone with whom you are so at ease with time stops, no problems bother you, there is no sadness to feel, only each other's presence and love. You get lost in time with this person, and everything just feels so right, and magical, and true. And you both don't realize it at the moment, but now that you look back, now that time has gone by, you can tell that when you where together time certainly stopped, for you and her.