How do I make a touch brick that make npc appear and disappear after awhile?

Put the NPC in storage and then call for it to be :cloned() to workspace by a script which detects when a block it touched :) then wait for a while the :destroy() it :)

If you wanted to make an NPC, for example, appear for maybe 5 seconds after a brick is touched we could do the following:

-- By using the RBXScriptSignal, or event, Touched, the script will detect when a block is touched

game.Workspace.OurBrick.Touched:Connect(function    

end)

Now, let's set up a few functions when the event fires

game.Workspace.OurBrick.Touched:Connect(function

    -- This function makes the NPC appear (or change position)

    local function npcAppear()
        local npc = game.Workspace.NPC
        local appearPart = game.Workspace.appearPart -- This is the block that the NPC will teleport to     

        npc:SetPrimaryPartCFrame(appearPart.CFrame) -- This will make the NPC teleport to the part

    end


    -- This function will make the NPC disappear

    local function npcDisappear()

        local npc = game.Workspace.NPC
        local disappearPart = game.Workspace.disappearPart

        npc:SetPrimaryPartCFrame(disappearPart.CFrame) -- The part it positions to should be in a place the player cannot see


    end

end)

So now that we have set up our functions to make the NPC appear/disappear, let's use them

game.Workspace.OurBrick.Touched:Connect(function


    local function npcAppear()
        local npc = game.Workspace.NPC
        local appearPart = game.Workspace.appearPart    

        npc:SetPrimaryPartCFrame(appearPart.CFrame)

    end


    local function npcDisappear()

        local npc = game.Workspace.NPC
        local disappearPart = game.Workspace.disappearPart

        npc:SetPrimaryPartCFrame(disappearPart.CFrame)

        -- Now we will use our functions and make the NPC appear and then disappear after 5 seconds     

        npcAppear()
        wait(5)
        npcDisappear()

    end

end)

So, to recap what we just talked about: We set up a connection when the .Touched event is fired. Inside the connection, we set up two functions, one to make the NPC appear and one to make it disappear. Inside these functions we used :SetPrimaryPartCFrame so that it would teleport the entire NPC and not just one part. Once we set up the functions, we used them to make the NPC appear for 5 seconds then disappear. I hope this helped you!