what does % mean in lua code example

Example 1: lua function

--// Basic Function

function PrintingText()
print("My text here")
end

PrintingText()

Example 2: What is lua used for

Lua is a powerful and fast programming language that is easy to 
learn and use and to embed into your application. 

Lua is designed to be a lightweight embeddable scripting language.
It is used for all sorts of applications, 
from games to web applications and image processing.

-- 

Used commonly in Roblox, Garry's Mod and Multi Theft Auto