Rocky Linux is a upcoming stable-focused GNU/Linux distribution based on Red Hat Enterprise Linux. It will be binary-compatible with RHEL and follow upstream development the same way CentOS did before CentOS went from being a stable distribution based on stable RHEL releases to a beta-quality test-bed for RHEL towards the end of 2020.
Rocky Linux development is lead by Gregory Kurtzer who founded the CentOS project.
There are no Rocky Linux releases as of February 2021. It is unclear when it will be released.