Bank or Cash are managed in Odoo by statements, for the bank transactions, the bank will be provided by a statement that has to be matched with the statement prepared in Odoo. In the statement, you have an opening balance list of transactions (debit or credit), and at the end, you have a closing balance. Usually, we receive a statement from the bank every month or whenever we have requested to receive the statement. With Odoo, we can manage a statement by month, half month, week or a day, depending on what you want.
We assume that you are ready with the Journals in Odoo as per the list of banks you have. For each bank, you have to decide how to import the statement. If you choose the statement synchronization from the bank, it would be an excellent option, as the statement will be imported automatically in Odoo.
If your bank is not available in the bank synchronization in Odoo, try to check the formats are given by the bank as an importable bank statement in Odoo. Odoo supports the QIF, OFX, SEPA, and CSV formats to import the bank statement.
Go for manual statement encoding when your bank does not support any of the automatic methods, such as synchronization, or import the statement.