In this video transcript, the teacher explains the meaning of the idiom "to put on the back burner" using context clues. The teacher emphasizes that idioms cannot be understood by looking at the individual words and encourages students to use surrounding words and sentences to figure out the true meaning. Through an example involving a toothpick project and a bakery trip, the teacher demonstrates that "to put on the back burner" means to set aside or postpone something for later. The lesson teaches students how to effectively decode idiomatic expressions.