CC0 stands for Creative Commons 0, a license applied by a creator/copyright owner to their work which removes copyright and effectively places the sound in the public domain. We are not the author of these sounds. These sounds are either sound effects listed as CC0 and freely distributable or sounds we've created by mixing them together to create new sound effects. We've been very selective and chosen to publish only sounds we feel are of the best quality. These CC0 sound effects can be used freely in your projects be them commercial, non-commercial and broadcast.
Visit their website for more: https://www.zapsplat.com