Using Sign Language Is a Bridge Language

i came across the idea of teaching children by lingl my wife's japanese, and i'm american. We want our child to grow up learning both as native languages. But it still may be a little confusing, creates a big challenge. And so i had already thought of the idea of using sign language,. So using sign language is a bridge language. What does that mean exactly? What are the advantages of that? Why do it? Well, first whall, think of a bridge. It connects, right? A bridge connects. I speak, i will be speaking only english. Im speaking only English.