For a teacher, time-fillers are activities that he/she would conduct in order to make full use of transition time. They are activities that will continue to stimulate the children's minds as well as keep them entertained. Time-fillers usually make a small part of the day's schedule. If the time-fillers are interesting enough, the children will remember them for life. Loving repetitions, interesting time-fillers will be requested again and again by children.
Time-fillers in a human context are people who just fill up another person's time when he/she is lonely. In lament terms, a substitute. When all else fail, one can always depend on a time-filler to be there.
I only fill your lonely hours but you fill my mind.