Discuss and learn French: French vocabulary, French grammar, French culture etc.
"à bientôt" means "see you soon"
"à tout à l'heure" means that you will meet the person in the next hours
It's a way to say goodbye to someone but you'll see him/her again this day
You can hear in a conversation "à t' à l'heure" where the word "tout" is contracted into "t' "