Every time there is a player vs. player kill or a suicide, it will be reported to you in chat and the location of the kill will be drawn on your HUD for a short period of time. A cyan box will be highlighted over the player as well so you can easily spot the attacker.
This addon is meant for servers with low instances of PvP. On servers where PvP is common, your chat will be flooded and your HUD will be filled, and thus this addon is not very useful in those cases.
Only administrators will see the deaths. This is a server-side addon.
On gamemodes that let people change their player name, you will have to modify the Lua file (where indicated) in order to support your gamemode, otherwise only the player's non-Steam name may be shown. If you use DarkRP, PVP Monitor is already configured to use Steam names provided by DarkRP.
It is recommended that administrators have some HUD addon that will draw players' names as this addon will not do that on its own.