Builder is a mod that allows server owners to have a much wider range of options when placing details on the map.
This is not the editor itself, but a mod to give you more options with the editor! You still need to download and use community offline mode. Watch the video.
For editing only: In order to get names of items already on the map you need to install this now: https://steamcommunity.com/sharedfiles/filedetails/?id=1570627596. Do not use it on client or server, only for offline mode.
Currently, Builder gives about ~1000 props, walls, roads, map objects, etc etc proper class configurations so that owners may use them as decoration or design of their map.
If you're just a player, all you have to do, is hit subscribe and forget about it, this mod doesn't really change anything as far as you're concerned.
For server owners, here's a guide on how to use this to increase your options when editing the map, and a guide on how to use COM for placing objects in general: https://youtu.be/2KX2tRTO-ag
Link to COM dev branch: https://github.com/Arkensor/DayZCommunityOfflineMode/tree/development