Under (one's) belt

Translation of "under (one's) belt" into Russian

за (чьей-то) спиной

Once you have a few successful projects under your belt, you'll feel more confident.

Когда у вас за спиной будет несколько успешных проектов, вы почувствуете себя увереннее.

Having gained experience or knowledge in a particular area or field.