Not sure what a journal or document will do to the ledgers? Preview it. Nothing is posted and you see every entry it would create.
On any document or journal, choose Preview Posting (Post → Preview, or the action). Business Central runs the whole posting, shows you the G/L entries, customer or vendor ledger entries, VAT entries, item ledger and value entries it would create, and then rolls back. Drill into any of them.
Use it before posting anything unusual (a credit memo with a charge, a journal to a control account, an intercompany document), to check which accounts a new posting group combination hits, and to train new users on what "post" actually does. It is also the quickest way to find a missing posting setup: the preview fails with the same error posting would, without a half-posted document.
