I can tell you're new to scripting in Lua language. First, everything needs to be lowercased, expect for functions, strings, comments, and variables. That means every keyword has to be all lowercase. Functions need a ':' in order to have that function to run. You may have to fix the script.WaitForChild() into script.Parent:WaitForChild(). The reason I added the Parent part there is because we are referring to the script's parent, or if you are referring to the script itself, then that's probably why. Another thing to note is that you do not put spaces between the function and the parentheses, otherwise the script will get confused.
local animation = script.Parent:WaitForChild('Animation')
local humanoid = script.Parent:WaitForChild('Humanoid')
local playAnim = humanoid:LoadAnimation('animation')
animation.Looped = true
playAnim:Play()
If this helped you, you're welcome and I hope you have a great day.