Loan demands are made by people trading on margin, ie. borrowing coins to either short them or to use them for leveraged trading.
Loan offers is people lending coins to margin traders as mentioned above, offering them for a certain duration (at least 2 days) for a predefined interest rate (defined per day).
If your interest rate is too high, no one will take a loan from you, as you will get undercut by other market participants. If your loan offer gets accepted, you will then get a daily yield based on your preset interest rate. Your coins will get returned to you either a) after the preset duration has passed, b) the margin trader closes their position or c) the margin trader gets hit by a margin call and has thus their position liquidated.
I have a question on this, how does lender ensure that they would get their coin back? Also for example I borrowed a loan then i tried to make a trade and unfortunately didn't succeed, how could he bounce back from this lose?