The order of the parts of the verse can be reversed. Alternate translation: "you will deny three times that you know me before the rooster crows this day"
This can be stated positively. Alternate translation: "the rooster will crow this day only after you deny" or "before the rooster crows today, you will deny"
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/jit/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." Alternate translation: "tonight" or "in the morning" (See: [[rc://en/ta/man/jit/figs-explicit]])