Vanessa focuses on a second everyday meaning of tell. Learners often know tell as saying or communicating information, as in “Tell me the answer” or “He told me what happened.” In this lesson, tell can also mean notice, determine, or recognize something from available information. She teaches this meaning through short examples and repeats each sentence with simpler paraphrases so learners can hear how the expression works.
The first example is “I couldn't tell if he was a boy or a girl.” Vanessa clarifies that it does not mean she could not say the words; it means she did not know or could not determine which was true. She also says “It was hard to tell,” meaning it was difficult to know. Adding by looking at his face identifies the evidence she used: “I couldn't tell by looking at his face.” The pattern tell if/whether is useful when a person is trying to determine which of two possibilities is true.
The second main example is “I can usually tell when someone is lying to me.” Here, tell means recognize or notice that someone may be lying. Vanessa paraphrases it as being able to see or know whether a person is telling the truth. This expression describes one's judgment from the situation; it does not guarantee that someone can always detect a lie. The video closes with a viewer challenge: write a sample sentence using tell in this sense. Vanessa offers to correct sentences if viewers ask. Learners can practise the distinction by asking what is being communicated in the first meaning, versus what is being detected or determined in the second. Useful patterns include tell me the answer, couldn't tell if, hard to tell, tell by looking, tell when someone is lying, and tell the truth. The short lesson is practical listening and vocabulary work rather than a comprehensive grammar treatment of every use of tell.