1Before the entry: the bank has a hundred million of its own
On the left are assets, what the bank owns: a hundred million sitting in its account at the central bank. On the right are liabilities and equity, where that money came from: the owners put it in. The totals are equal, and that is not a coincidence — a balance sheet balances by construction.
2A line appears on the left: “Loan to Irina”
An asset is somebody else's obligation to the bank. Irina owes a hundred million back, and the bank records that obligation among its assets. No money moved anywhere: a record of a debt appeared.
3A line appears on the right: “Irina's account”
A liability is the bank's own obligation. Money in a customer's account is a debt of the bank to the customer: it must be handed over on demand. Having issued the loan, the bank credited the sum to the account — and owed Irina exactly as much.
4Both totals grew at once — from 100 to 200
The bank did not take money out of a vault and did not borrow it from a neighbor. It made two records, and a hundred million appeared in Irina's account that had not existed a second earlier. This is how money is created in a modern system — by a commercial bank's entry, not by a printing press.
5Why this cannot be done another thousand times
Irina will spend the money and it will leave for another bank — settlement takes reserves, and the bank has a hundred million of them, not an endless supply. Add capital requirements and the liquidity ratio. Those limits are chapters 2 and 4; the mechanics are the same, only reality plays against you.