The phrase "against loss" is an idiomatic expression that means to take preventative measures or precautions in order to avoid a negative outcome. It can be used in various contexts, such as financial planning, risk management, and personal safety. For example, someone might say they are "covered against loss" if they have insurance for their valuable possessions, while an investor may take measures "against loss" by diversifying their portfolio to minimize potential risks. Essentially, the phrase implies that one is being proactive in protecting oneself from harm or financial damage.