used to mean that time passes surprisingly quickly
زمان به سرعت میگذرد
Time flies when you’re with friends having great time.
time ˈflies idiom
(saying) time seems to pass very quickly
• How time flies! I've got to go now.
• Time has flown since the holiday began. This phrase is a translation of the Latin ‘tempus fugit’.
Cambridge Advanced Learner's Dictionary - 4th Edition
time flies saying
C2 used to mean that time passes surprisingly quickly:
Time flies when you're having fun.