Try this instead. I don’t see any problems with your code otherwise.
local serverstorage = game:GetService("ServerStorage")
local overhead = serverstorage:WaitForChild("Overhead")
local billboard = overhead:WaitForChild("Overhead"):Clone()
local label = billboard:WaitForChild("RasenLabel")
billboard.Parent = char:WaitForChild("Head")
local text = 'Rasengan'
for i = 1, text:len(), 1 do
label.Text = text:sub(1, i)
task.wait(.1)
end
sub is a function in any string object which returns the sequence of characters between 2 indices (positions). So string.sub("apple", 1, 3) would return "app". This is the same as doing "apple":sub(1, 3) .
len is also another function which returns the length of a string.