small bamboo basket for holding
簞 refers to a small bamboo basket used for holding things, typically food or other items.
簞 combines 竹 (bamboo) with 單, which likely contributes a phonetic element. The character originally depicted a bamboo basket.
The top 竹 is bamboo, and the bottom 單 looks like a simple container. Picture a small, simple bamboo basket for holding rice or snacks.
For タン, imagine a tan-colored bamboo basket holding your lunch: tan -> タン.