Here, the crowing of the rooster refers to a certain time of day. Roosters often crow just before the sun appears in the morning. Therefore, this refers to dawn. (See: [[rc://en/ta/man/translate/figs-metonymy]])
The Jewish day begins at sunset. Jesus was speaking after the sun had set. The rooster would crow just before morning. The morning was part of "this day." AT: "tonight" or "in the morning" (See: [[rc://en/ta/man/translate/figs-explicit]])