Can someone what error I have on this?

x = Instance.new("Part")
Attack = script.Parent

function onTouched(Part)

if Part:FindFirstChild("Humanoid") == nil then
 script.Disabled = true
 numberofbricks = math.random(6,15)

 for i = 1,numberofbricks do

 PartSize = math.random(1,4)
 x.Size = Vector3.new(PartSize, PartSize, PartSize)
 x.CFrame = Attack.CFrame
 x.Parent = game.Workspace
 x.BrickColor = Part.BrickColor
 x.BottomSurface = "Smooth"
 x.TopSurface = "Smooth"
 wait()
end
end
end
Attack.Touched:connect(onTouched)

So the first thing i noticed is that you are looking for the character's humanoid inside the part, wich is certainly not usefull.

Let's try at your line 6, replace it to:

if Part.Parent:FindFirstChild("Humanoid") ~= nil then

Why ~= nil? Because, i noticed you want it to find player's touch, but every character, is it NPC or Player has a Humanoid. Your script wouldn't work either way.

~= means Isen't

Also i noticed at line 8 you use a math.random function incorrectly, wich is causing the error.

The math.random function works as math.random(Number,OutOf). So basically you were using 6 numbers out of 15, wich automatically errors, because its a number array (numbers = {})

So, let's try the array method. MathRandomNumerOfBricks = {6,7,8,9,10,11,12,13,14,15} That stores every number that could be in math.random(6,15)

We use: MathRandomNumberOfBricks[] to get a stored value from it. math.random(1,#MathRandomNumberOfBricks) inside the [] to get one value from the array.

So our final script will be:

x = Instance.new("Part")
Attack = script.Parent

function onTouched(Part)

if Part.Parent:FindFirstChild("Humanoid") ~= nil then
 script.Disabled = true
MathRandomNumerOfBricks = {6,7,8,9,10,11,12,13,14,15}
 numberofbricks = MathRandomNumberOfBricks[math.random(1,#MathRandomNumberOfBricks)]

 for i = 1,numberofbricks do

 PartSize = math.random(1,4)
 x.Size = Vector3.new(PartSize, PartSize, PartSize)
 x.CFrame = Attack.CFrame
 x.Parent = game.Workspace
 x.BrickColor = Part.BrickColor
 x.BottomSurface = "Smooth"
 x.TopSurface = "Smooth"
 wait()
end
end
end
Attack.Touched:connect(onTouched)

Hope this works! If not, tell full output. ~marcoantoniosantos3