How do i make it for it will keep adding 10 not just add it one time?

You have to add each value individually.

x = script.Parent.Position.X
y = script.Parent.Position.Y
z = script.Parent.Position.Z
while true do
    for i = 1,10 do
        print(script.Parent.Position)
        wait(2.5)
        script.Parent.Position = Vector3.new(x + 10,y + 10,z + 10)
        print(script.Parent.Position)
    end
end