To allow or permit someone to do something in English, you can use the phrase "let someone" or "let someone do something." For example, you could say "Let me help you with that" or "Let's go for a walk." The phrase "let someone" comes from the Old English word "lettan," which means "to hinder or prevent." Some other examples of sentences using this phrase include "Let's go to the park" and "Let's go to the movies."