State in computer science basically means something that remembers its current condition or status. Imagine you have a toy car and it has a button on it - when you press the button, the car moves forward. The car remembers that it was at rest before you pressed the button, then after you pressed the button it remembers that it started moving.
This is an example of state. When you pressed the button, the toy car's state changed from "at rest" to "moving forward."
In computer science, state is important because it allows programs to keep track of what is happening and what has already happened. For example, if you're playing a video game, the game needs to know what level you're on, what items you've collected, and how many lives you have left. All of this information is stored as state.
State can be saved and retrieved at any time, so you can pause the game and come back to it later without losing your progress.
Overall, state is a way for a program or device to remember what it's doing and what has been done, so it can continue to work properly and efficiently.