に

に is the most polysemous particle in core Japanese — one form covering destination, recipient, location of being, and a fixed point in time.

Destination: 学校に行く — "go to school." Recipient (indirect object): 友達にプレゼントをあげる — "give a present to a friend." Static location with ある/いる: 駅に銀行がある — "there is a bank at the station" (use で for the location of an action, に for the location of existence). Time: 七時に起きる — "wake up at seven" (only with specific clock-times, dates, days; not with vague times like 今日, 朝).

The に / で contrast for locations is the most-asked follow-up question. 駅にいる = "is at the station" (state of being there). 駅で待つ = "wait at the station" (action happens there). "Wait" is an action, so で; "is" is existence, so に.