A pooled investment is like when you and your friends put your money together to buy a toy or game you all want to play with. Adults do this too, but instead of toys, they put their money together to buy things like stocks or bonds.
When they do this, they can buy more of these things than they could if they were just buying them alone. This is because they have more money to put in, so they can buy more expensive things that will hopefully make them even more money in the future.
The person or group of people who manages the pooled investment is called a fund manager. They make decisions about what to buy and sell, and how much of each thing to buy with the pooled money.
When the investments make money, everyone who put their money into the pool gets a share of the profits, based on how much money they put in. But if the investments lose money, everyone loses some of their money too.
Overall, a pooled investment is just a way for people to work together to make more money than they could on their own.