How to insert text into script while ingame?

You know how in certain admin scripts when you ban or admin a player the player's name actually get's added in text form into the script. Which I've been wonder now how?

###That is called concatenation. To concatenate a string, you use two dots (..), with the .. in between the two strings you want to concatenate. Take this script for example:

game:GetService("Players").PlayerAdded:Connect(function(player)
    print("Player with the name "..player.Name.." has joined.")
end)

###Since my username is incapaz, that should print "Player with the name incapaz has joined."

print("Concatenation ".."is ".."cool")
--> Concatenation is cool

You can have a table list of strings (names) and can add strings by using table.insert.

local Admins = {"sample"}

--use table.insert to insert a new string into the Admins table
table.insert(Admins, "newName") -- The first array is the name of the table. The second array is the value/object you are inserting inside the table