I used this type of communication cards for 15 years in my classroom. Somewhere along the way, I discovered I could make them easier to use if I put tabs to find the cards quicker. They were used by most adults that came into my room working with students that are nonverbal.
Picture cards are an effective way to communicate with students who do not understand language. The picture paired with either American sign or spoken words help the child to learn what the words or sign mean. I believe the picture cards should always be paired with language. The language appropriate to say with the card is printed on the card.
Many people say too many words with children who have a hard time processing language. If adults will say the same short phrase every time that the picture is shown, the child's understanding will increase quickly.