Bank prudential management.
Broadly speaking, in bank funding and capital management, 'own funds' means the bank's own capital.
Own funds are a very stable source of funding, because there is either no contractual obligation to repay them, or only a limited obligation.
Other sources of the bank's funding are 'borrowed' funds.
The Capital Requirements Regulation defines a bank's own funds as the sum of its Tier 1 capital and Tier 2 capital.
In other contexts, the term 'own funds' is also used in a narrower sense, limited - for example - to the bank's equity capital (CET1).