What is the meaning of で?

The hiragana syllable で (de). Its equivalent in katakana is デ (de).

at, in:

1. indicating a location or duration at which something happens

   indicating a location or duration at which something happens

   (Can we verify this sense?) indicating the carriage of something

   with, by, using: indicating the means by or with which something happens

   indicating the following sentence is a consequence of something previously stated: and then; therefore

   is/am/are ... and: the て-form or conjunctive form of だ (da)

   used after godan verbs ending in -gu, -bu, -mu, or -nu form of て

   Attaches to the 未然形 (mizenkei, “irrealis or incomplete form”) of verbs to form the negative conjunctive, equivalent to the modern ないで (-naide) or ずに (-zuni).

   sentence-ending particle signifying emphasis

   Source: wiktionary.org