In this video, the teacher explains the meaning of the idiom "to burn bridges" using context clues. The lesson emphasizes that idioms cannot be understood by looking at the literal meaning of each word, and instead, learners should rely on the surrounding words and sentences to grasp the intended meaning. The example of quitting a job and the potential consequences of damaging professional relationships is used to illustrate the importance of not burning bridges. The video provides step-by-step guidance on how to decipher the meaning of idioms by imagining the literal interpretation, seeking context clues, and creating a visual representation.