Let's start by saying that monads are difficult to grasp at first. It might take you some time and a couple of attempts to really even start to have an understanding of them, so don't worry if they seem overwhelming at the start.
Like functors and applicatives, monads provide an abstraction for chaining operations that allows us to structure our programs generically and avoid code duplication. This abstraction allows us to simplify problems like handling exceptions during execution (which we will explore shortly) by building succinct pipelines without needing to worry about flow control or side effects.
Many types we already encountered as pre-defined in Haskell are also instances of the Monad typeclass, including Maybe and List.