席を予約したいのですが。

seat; location (of a gathering, etc.); place; position; post

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

reservation; appointment; booking; advance order; contract; subscription; pledge

indicates possessive; nominalizes verbs and adjectives; substitutes for "ga" in subordinate phrases; (at sentence-end, falling tone) indicates a confident conclusion; (at sentence-end) indicates emotional emphasis; (at sentence-end, rising tone) indicates question

be; is

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and