This is the 4737th most frequent Russian word.
задолженность
"Задолженность" means "debt" or "outstanding obligation."
Here, 'задолженность' is used metaphorically to describe required but incomplete coursework or academic obligations.
У студента накопилась задолженность по учебным предметам.
The student has accumulated debts in academic subjects.
In this sentence, 'задолженность' refers to financial debt owed by the client to the bank.
Банк предъявил клиенту задолженность по кредиту.
The bank presented the client with unpaid debt on the loan.
Here, the term is used to describe unpaid wages due to employees.