There are a lot of problems with this script.

Loops

This script is ridiculous. You should have stopped yourself before you got here and asked, "Is there a better way?" because the answer is a resounding yes.

Use a loop.

local lights = script.Parent.Lights:GetChildren()
-- You could use `script.Parent.Lights["l" .. i]` instead of sorting, but this is cleaner
table.sort(lights, function(a, b) return tonumber(a.Name:sub(2)) < tonumber(b.Name:sub(2) end)
-- (You could also sort by `x` or something similar)

for i = 1, 9 do
    -- Start by turning them all off
    for j = 1, #lights do
        lights[j].PointLight.Enabled = false
    end
    -- Turn every 10 on, starting with the `i`th one
    -- (1, 11, 21, ...)
    -- (2, 12, 22, ...)
    -- ...
    -- (i, i+10, i+20, ...)
    -- ...
    -- (9, 19, 29, ...)
    for j = i, #lights, 10 do
        lights[j].PointLight.Enabled = true
    end
    wait(0.03)
end

Positions

Positions aren't functions. x(y) is only used for functions.

Positions are Vector3s. To make new Vector3s, we use the Vector3.new(x, y, z) constructor function.

while workspace.Rocket.Engine.Position == Vector3.new(300.004, -252.007, 62.4) and workspace.Rocket.Engine2.Position == Vector3.new(310.2, -252.007, 62.4) and ....

Comparing positions is a bad idea. If the thing moves at all, even trillionths of a stud, the comparison will fail. If the object is not anchored, this is all but guaranteed. If the object is anchored, there is very little chance of returning it precisely to this spot if it ever leaves.

You should probably consider a different way to determine if it's done.

Also note that it's really strange to use both the repeat and while. What were you trying to accomplish?