Can you please explain me the deep meaning of the first night of Passover. I once heard it’s full with high lights. Lights that appear only by then.

Rav Kook (Igrot 378) writes that every day has its own “lights” and special impact on the world, Pesach is the festival of freedom and so is its impact on the world. Try looking into the different Chassidic writings for a full deep meaning of the first day on Pesach.