Okay imagine you and your friend want to play a game. But before you start playing, you need to agree on the rules of the game so you can both play together. Otherwise, there might be arguments and fights while playing the game.
The same goes for countries that want to work together. They need to agree on some things before they start working together to avoid arguments and fights. In 1992, China and Taiwan agreed on something called the "1992 consensus". This means they agreed on the rules for how they will work together even though they have different ideas about who should be in charge of Taiwan.
The "1992 consensus" is like the rules of the game that China and Taiwan agreed on before they started working together. It helps them to avoid arguments and problems and work together peacefully. So, just like you and your friend, China and Taiwan decided to agree on some rules to work together harmoniously.