You need to install 2 things for a live TV setup in Kodi: A program called "backend" or "server" that will "see" the hardware, operate manage the hardware ( ie setup all needed hardware settings, scan for channels, tune in to a channel, ...)
and a program called the "frontend", best known as PVR client, a Kodi addon.
IMHO best by far is the TVHeadend.
No worries, BOTH programs needed come with Libreelec, and its just a click to install them.
First, the "backend", its a script, fo to addons, install from repository, browse in Libreelec repository, SERVICES, you ll find it there. Click, select, install. Easy!
Runs in the backround as a service
Then, you have to do some work, before installing the PVR Client in Kodi and enable TV in Kodi, you have to setup the backend. As explained above, you can setup the tuner and scan for channels, setup channel names, numbers if you like, and more... There are some video tutorials around about this, i have found very detailed and easy to follow this one: How to configure tvheadend server - YouTube
After finishing with backend server setup, you can go ahaid and install the TVHeadend PVR addon in Kodi ( also found in Libreelec repository with all the rest PVR plugins)
No need to configure the PVR addon, all default settings should work OK.
Last, enable TV in Kodi, done.
Sounds complicated, its not. Maybe first time when you dont have any experience with the backend server part, if you follow the video instructions step by step you should be OK 