で
At, in (place where an action happens)machine translation
FormationNoun indicating a place + で + verb
で goes after a place noun to mark where an action takes place: 図書館で勉強します (study at the library), レストランで食べます (eat at a restaurant).
Don't confuse it with に: で is for the place where an ACTION HAPPENS, while に is for where something exists (〜にあります・〜にいます) and for the destination of movement. Compare: 学校で食べます (eat at school — action) with 学校にいます (be at school — existence).
This is the particle pair Vietnamese speakers mix up most, since both translate as "ở" (at). Tip: look at the verb at the end of the sentence — if it's an action (eat, read, play, work), the place takes で.
Examples
図書館で本を読みます。
I read books at the library.
レストランで昼ご飯を食べました。
I ate lunch at a restaurant.
公園で写真を撮りました。
I took photos at the park.