How do I make a script changes the colour of a brick to whatever it touches? [SOLVED]

The color of a part is specified by its BrickColor property.

To get or set the color of a part, we get / set its BrickColor property.

The brick you want to change colors I call colorblock here; it could be script.Parent or workspace.Flashing or anything else you want.

When something touches colorblock, it fires its Touched event.

When the Touched event fires, it passes a parameter of the part touching colorblock. We get that touching part's BrickColor, and set colorblock's BrickColor to that.

It could look like this:

function BlockTouched(partTouching)
    local newColor = partTouching.BrickColor;
    colorblock.BrickColor = newColor;
    -- `partTouching` is a parameter
    -- passed that is the part that touched
    -- `someblock`.
    -- We just copy its `BrickColor` to `someblock`'s `BrickColor`.
end

colorblock.Touched:connect(BlockTouched);

Where someblock is a reference to the brick which will change color.

If we want to ignore certain touches, like, for instance, the base plate, we would have to check whether or not the object is one we want (or alternatively anchor it, so that it doesn't touch other anchored objects):

function BlockTouched(partTouching)
    if partTouching.Name ~= "BasePlate" then
        local newColor = partTouching.BrickColor;
        colorblock.BrickColor = newColor;
        -- Ignore parts named BasePlate
    end
end

colorblock.Touched:connect(BlockTouched);

Or we could also check that partTouching isn't anchored:

if not partTouching.Anchored then

(although this may not be what you want)