Operation Pocket Money was a plan made by the United States government to block North Vietnam's access to their supplies by bombing their waterways during the Vietnam War. It was called "Pocket Money" because it was meant to put a hole in their pocket and make it harder for them to transport goods.
Imagine that you have a basket of toys, but your friend keeps taking things out of it. So, to make sure they can't take anything from you anymore, you put a big rock in the path that they always take to get to your basket. This is kind of like what the United States wanted to do to North Vietnam. They wanted to make it harder for them to get supplies by blocking their waterways, which were like roads for boats.
The U.S. government sent planes to drop bombs in the waterways to make them too dangerous to use. This made it hard for North Vietnam to get supplies like weapons and food. The plan was carried out from 1965 to 1972, and although it did make things harder for North Vietnam, it also caused a lot of damage to the environment and harmed innocent people who lived in the area.