When we exaggerate we stretch the truth. For example "I've done that a million times" would be an exaggeration. (Of course, if the person really has done it a million times it wouldn't be an exaggeration.)
Here's another: "He's a strong as a bull." (He's strong, but he's not really as strong as a bull.) And another: "I could eat a horse."
Such phrases are quite common.
Student or Learner