In terms of a state of being, 'on' is used as adjective to express activation, such as when something is 'on' or 'off'. For example, a light switch can be 'on' (active) or 'off' (inactive).
a preposition is a word that shows the relationship between a noun or pronoun and another word in the sentence. They signify where, when, or how the subject is related to another word. Prepositions always come directly before their objects; in English, these are usually nouns, pronouns, or noun phrases.
when using 'on' as a preposition, it is most often used to indicate position, time, or a method or manner of an action. It can also mean 'upon' when discussing a surface, such as a table or chair, and is generally used to describe an action being done to or at a location in order to indicate the manner or purpose of the action.
1. I usually hang my coat on the hook by the door.
2. The meeting was rescheduled for Tuesday on August 19th.
3. He climbed on the ladder to reach the top shelf.
if you are unsure whether to use 'on' or 'in' as a preposition, remember that 'on' usually indicates a specific location of contact with a surface or object, while 'in' is used to describe a location within an area or boundary. Additionally, you should not use an article such as 'a' or 'the' before the preposition 'on'.