Search by sound means that you can look for things by the noises they make, instead of just by their name or picture. Just like when you play "I Spy" with your friends, you can recognize a person, animal, or object based on what they sound like.
For example, if you hear a bird chirping outside, you can use your ears to search for where the bird is sitting. Or, if you hear a song on the radio and you don't know what it's called or who sings it, you can use a search tool that listens to the song and tells you what it is.
In more technical terms, search by sound uses algorithms (like a set of rules or instructions) that can analyze sound patterns and match them to a pre-existing database of sounds. This allows the computer to find exactly what you're looking for based on the unique sound that it makes. So, the next time you hear a sound and you're not sure what it is, you can ask your computer to help you find out!