A piece of information is a piece of knowledge. The word comes from Latin and is related to our word "form", in the sense of appearance or shape. At a bus stop, for example, you will find a table with information about when the buses leave. When we think of "information" we think of something small and specific, when we think of "knowledge" we tend to think of a lot of information in one context. Information is more what is in the computer or on the bookshelf, knowledge is what someone has in their head.
The word information can mean many things. Mostly, one thinks of knowledge itself. But there are also places called "information", for example in a railway station or the tourist information in a city. Another word for it would be "information".
You often only understand information when you know the context, when you know what you can use it for. If a car costs ten thousand euros, you have to know exactly what kind of car it is and where you can get it for that price. Information that you have stored in a certain way in certain places is also called data. A lot of data together can be stored in a database.