How to use Remote Function?

As far as I understand remote function needed in order to send information from script to local script and and make the requested action on the server. Okay, i watched a lot of videos and read a lot of explanations on the forums, but i still didnt understand how to use Remote Function. I have 1 script and 1 local script. I need players who have BoolValue = false to have Speed = 0 at a certain point. I could use RemoteEvent, but it easy to exploit, so thats why i want Remote Function. For example:

--Script
speed = 0
game.ReplicatedStorage.Speed:InvokeClient(speed)

--Local Script
local function teleportdetected(speed)
    if Value == false then
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = speed
    end
end

game.ReplicatedStorage.Speed.OnClientEvent:Connect(teleportdetected)