Use these sources to learn more about LVM.
rpm -qd lvm — This command shows all the documentation available from the lvm package, including man pages.
lvm help — This command shows all LVM commands available.
https://sourceware.org/lvm2 — LVM2 webpage, which contains an overview, link to the mailing lists, and more.
https://tldp.org/HOWTO/LVM-HOWTO/ — LVM HOWTO from the Linux Documentation Project.