I tried this:
local plrs = game.Players:GetPlayers
function findPlayer(message,speaker)
if (string.sub(message,1,5) == "kill/" and (string.sub(message,7) == plrs.Name then
print("kaboom.")
end
This script is trying to match a chat message with an object, but this won't work.

5 comments
Line1: ':GetPlayers' should be ':GetPlayers()" it is a function, don't forget the parentheses.
If you're trying to find who said that then you should use Chatted.
game.Players:FindFirstChld(message:sub(7,-1))
You seem to not understand how tables work, or the function GetChildren/GetPlayers.
Here's a good explanation of tables, https://scriptinghelpers.org/questions/28182/how-to-learn-tables#31632