1.168 generalizing
Another group of nouns which can be used with just 'the' are nouns which are normally count nouns but which are used in the singular to refer to something more general.
For example, you can use 'the theatre' or 'the stage' to refer to all entertainment performed in theatres. Similarly, 'the screen' refers to films in general, and 'the law' refers to the system of laws in a country.
Some nouns which normally refer to an individual thing or person can be used in the singular with 'the' to refer generally to a system or service in a particular place. For example, you can use 'the bus' to refer to a bus service and 'the phone' to refer to a telephone system.
Nouns referring to musical instruments can be used in the singular with 'the' when you are talking about someone's ability to play a particular kind of instrument.