Таможенное оформление — выполнение необходимых формальностей, процедур возникающих в связи с перемещением через таможенную границу товаров и транспортных средств.
If you are engaged in the export or import of goods, then you regularly have to deal with customs. After all, in accordance with the legislation, all goods that cross the border of Russia must pass customs clearance. This is necessary in order for the state to be able to control foreign economic activity.
Everyone who has ever carried out customs clearance knows how difficult this procedure is. 
It requires care, knowledge of the legal framework and a lot of time.