Module 5: Return on Equity

Hi,
I have a question in relation to module 5 on ROE. Below is an excerpt of the explanatory notes below the video:

A company pays for the stuff it owns (assets) either by borrowing money (liabilities) or by getting it from shareholders (shareholders’ equity). When a company chooses to borrow a lot of money over using shareholders’ money, liabilities increase while shareholders’ equity decreases in tandem.
When shareholders’ equity is reduced, ROE is increased as now the same amount of net profit is generated using less shareholders’ equity. Even though the company can achieve a high ROE this way, it is is now exposed to more risk; banks can increase interest rates or call back the loan at any time.

The underlined part puzzles me. My understanding is that, no matter how much money a company borrows from banks or other sources, the shareholders’ equity should remain unchanged. Through a bit of research on google, I have formed the understanding that, if a company’s asset consist of a first portion of liability and a second portion of shareholder equity, the return is attributed to the asset, more particularly to both the first portion and the second portion. Therefore, if a potential investor does not consider the first portion (the liability), he or she would be gullible to believe that the whole of the return is earned by the company using only the second portion, which makes the ROE seems larger than it really is.
It would seem to me that, if the first portion of liability accounts for 90% of the asset and the second portion of shareholder equity accounts for only 10%, then 90% and 10% of the return are attributed to the liability (borrowed money) and the shareholders equity, respectively. Is my understanding correct?
Can someone confirm my understanding please? Thank you!
Tony