I'm writing a banking software that, using some accounts from a bank, show the records about it. They could be debt records (money leaving account) or credit records (money arriving). Is there a specific word for the unit inside this group of records that together build the account history? I'm a Brazilian and using Google Translate, I searched for "lançamento". But this ambiguous portuguese word also means launch (like a rocket launch), which I think is not the case. I also found release, but I also think that's not the case (like a software being released into the consumer market). The word "lançamento" means to input/throw/launch(?) some data into an account.
Google translate provides a number of additional suggestions aside from "launch", including the one I think you're looking for: "entry". A financial record (or journal) is a record of individual entries for a particular account. These entries are (usually) either debits and credits to that account. Example:
Double-entry bookkeeping, in accounting, is a system of bookkeeping so named because every entry to an account requires a corresponding and opposite entry to a different account.
A journal entry is a formal accounting entry used to identify a business transaction. The entry itemizes accounts that are debited and credited, and should include some description of the reason for the entry, as well as the date.
If properly documented, journal entries provide an excellent audit trail for anyone investigating the accounting records of an entity.
Adjusting Journal Entry: An accounting entry made into a subsidiary ledger called the General journal to account for a periods changes, omissions or other financial data required to be reported "in the books" but not usually posted to the journals used for typical period transactions.
As Tᴚoɯɐuo says in a comment, I think transaction is a good word to use here. It's common and readily understandable, but not overly informal.
Most monthly bank statements include a "transaction history" which shows the debits and credits to an account.