Newbie, you have fallen victim to the Sage-monster. Try printing out a "Transactional Trial Balance" for the dates of your accounting year, then a "Period Trial Balance" to your year end. Experiment by including or excluding brought forward balances (there's a tick box option). Now take a balance sheet account without too many entries in it - a bank deposit account, or a plant and machinery account, maybe - and compare the differences in the nominal ledger reports (ie all the component figures that make up each balance in those TBs). That way you'll begin to understand the rudiments. Your printouts may vary according to whether or not you went through the year end routine in your accountancy software.
You're not alone in being unable to understand your printouts - most business owners can't either. Come to that many accountants struggle too. Just recently I made a few adjustments to a client's "books" (not Sage, but similar, and HMRC approved software to boot) - just straightforward postings to get payments from the suspense account and into the purchase ledger, and allocate payments to purchase invoices - and then printed out a VAT return. The result was a £1k repayment, which didn't look right to me; so I logged out, logged back in again, ran another VAT return and this time had a £5k repayment, which looked more like it. I haven't figured out whether the rule is that the VAT routine takes no notice of postings in the current session, or whether the glitch occurred because I had pulled up the previous quarter's VAT report prior to running the first (£1k) VAT report for the present quarter. Either way, it ain't supposed to happen, and makes me wonder whether we were all better off with a straightforward set of books: a cash-book, purchase ledger and daybook, and sales ledger and daybook, that didn't try to replicate the entire balance sheet and which business owners (and I) better understood.