Canadian slang for "Bye", "Take care", etc. more specifically used in the city of Ottawa. It can be used in various contexts, whether you're leaving a place, ending a conversation, or saying farewell to someone who is departing.
Could be shortened to just, "One".
Also written on text sometimes as, "1t".
1: "I'ma head out, bro, one time, fam"
2: "Alright, one time, holla at me"