bed
The German word 'Bett' is used to refer to a piece of furniture that is used for sleeping. It is a noun and can be used in both singular and plural forms ('Bett' and 'Betten', respectively). The word is pronounced similarly to the English word 'bet' but with a 't' sound at the end.
I'm going to bed.
This sentence is used to express someone's intention to go to sleep for the night. 'Ins Bett' here refers to going to the bed.
The bed is very comfortable.
This is a simple statement expressing comfort in the bed. 'Das Bett' refers to 'The bed' in English.
He reads a book in bed.
This sentence describes an action taking place in bed, expressed by 'im Bett'. In this case, the action is reading a book.