As most with most commands, the manual usually helps:
$ man lsb_release
The lsb_release command provides certain LSB (Linux Standard Base) and distribution-specific information.
Which leads to:
$ man lsb
lsb - Linux Standard Base support for Debian
The lsb package provides infrastructure for installing Linux Standard Base applications on Debian. This manual page is designed to refer system adminstrators and others to the documentation available.
The Linux Standard Base is a common runtime environment for third-party packages. The goal of the LSB is to make it easy to create binary packages that will run on any Linux distribution. For more information on the standard, please see the LSB web site.