It sounds like you're referring to the phrase "pack" in the context of preparing for rain. This generally means to gather and secure your belongings, especially things that might get wet or damaged, such as electronics, documents, and clothing. When it rains, people often take extra precautions to keep their items safe and dry, which might involve putting them in waterproof bags or containers.
If you're preparing for an exam or need more information on a specific aspect of this phrase or related concepts, feel free to ask!