The underlined expression "Don't cry over spilt milk" means that it is useful not to bemoan one's loss. It is an idiom used to encourage someone to avoid being upset about something that has already happened and cannot be changed. The expression suggests that crying or being upset will not fix the problem or change the outcome, and it is better to accept the situation and move on. It emphasizes the importance of being practical and not wasting time and energy on things that cannot be changed.