These are prepositions. To - - - can be used in various ways, but as a preposition it points out an object/place where you direct your verb/action. ex. She will go to the mall. (go->to->mall) go-verb/action word to-preposition mall-place (noun) directed by "go" In - - - same function (preposition) but refers to a specific location which is inside ex. The cat is sleeping in the house. (sleeping->in->house) sleeping-verb in-preposition house-place On - - - when the location is on/on top of something ex. I placed the mug on the table. (placed->on->table) placed-verb on-preposition table-location (on top) Of - - - is a function word, component, reason or possessive (ownership) ex. She died of flu. <--- reason A cold cup of water <--- component etc.

There are so many ways these words can be used. 'It' is a pronoun relating to an object. e.g. Where is the book? It is on the table. The other words are prepositions, usually showing placement or relationship, and commonly form part of phrasal verbs. If you are more specific with your question, we can give a more specific answer.