Why does my script doesn't react to Bolean value?

This is because a BoolValue has a property called Value which is where you can read/write the bool from

if script.Parent.Parent.Bool.Value == true then
    for i = 1,70 do
        script.Parent.Position.Z = script.Parent.Position - Vector3.new(0,0,0.05)
        wait(0.001)
    end
    wait(5)
    for i = 1,70 do
        script.Parent.Position.Z = script.Parent.Position + Vector3.new(0,0,0.05)
    end
end

you need to register an event listener to to the Bool value

because if you just write the following code, then when the game starts it will immediately run the code, only once..

if script.Parent.Parent.Bool == true then
    for i = 1,70 do
        script.Parent.Position.Z = script.Parent.Position - Vector3.new(0,0,0.05)
        wait(0.001)
    end
    wait(5)
    for i = 1,70 do
        script.Parent.Position.Z = script.Parent.Position + Vector3.new(0,0,0.05)
    end
end

but if you register an event handler to the bool value then the code will always run everytime that an event occurs;

the event you can use is called Changed. and here is how you can use it..

local bool = game.etc.ect.Bool -- change to directory of the bool value

bool.Changed:Connect(function()
    if script.Parent.Parent.Bool == true then
        for i = 1,70 do
            script.Parent.Position.Z = script.Parent.Position - Vector3.new(0,0,0.05)
            wait(0.001)
        end
        wait(5)
        for i = 1,70 do
            script.Parent.Position.Z = script.Parent.Position + Vector3.new(0,0,0.05)
        end
    end
end)

note: Changed listens for when any changes occur on the subject object; you can use GetPropertyChangedSignal to listens for only a single property like so:

local bool = game.etc.ect.Bool -- change to directory of the bool value

bool:GetPropertyChangedSignal("Value"):Connect(function()
    if script.Parent.Parent.Bool == true then
        for i = 1,70 do
            script.Parent.Position.Z = script.Parent.Position - Vector3.new(0,0,0.05)
            wait(0.001)
        end
        wait(5)
        for i = 1,70 do
            script.Parent.Position.Z = script.Parent.Position + Vector3.new(0,0,0.05)
        end
    end
end)

the above code only listens for when the Value Property changes~

you can find out more about events on:

Youtube

Roblox API reference

thank you!