“sei” is the imperative form for “du” (you, singular informal) of the verb sein. It is used to give instructions, advice, or encouragement. Examples: Sei offen. → Be open. Sei kreativ. → Be creative. Sei fair. → Be fair. All of these follow the same pattern: “Sei adjective.” They express a request or command telling someone how to be. Although “sei” looks the same as the subjunctive (Konjunktiv I) form of sein, in these sentences it is clearly the imperative, because it is used as a direct instr