What is the specific location it is searching for?

I am trying to make a basic inventory GUI where items are stored inside a folder in the Player and when you equip a tool from the GUI is clones it to the player's backpack. I was looking at an open source inventory GUI that essentially forces the player to hold the tool.

function search(location)
    for i,v in pairs(location:GetChildren()) do -- Find all item in a specific location
        if v:isA("Tool") then -- If the item found is a "Tool"
            table.insert(items,v) -- We're going to put all the tools found in a table.
        end
    end
end

It says "Find all item in a specific location". My question is what location is it searching for exactly?

P.S If you have any idea's for how I could go about making the inventory system please do tell me.