English equivalent of this Tagalog proverb [duplicate]

It’s likely that the closest equivalent is “closing the barn (or stable) door after the horse has bolted”.

Other phrases with related meanings would include “a day late and a dollar short” or simply “too little, too late”.

You could say that an action is simply rearranging deck chairs on the Titanic. The mental picture is that this is done as the ship is sinking. It does not match the notion that, earlier, the action might have helped, but does capture the futility.

You can also say that has missed the boat or the train has left the station. The mental picture is that they were too late to board, and lost the opportunity.