Interest Charges on Debit Balance

What does Interest Charges on Debit Balance mean? I was going through the pricing of angel one and noticed these charges. Can someone please explain?

See this article and possible reasons of debit balance

I see a deduction "Delayed payment charges" on my ledger. Why is this?.

Interest charges on debit balance means - the balance wherein you owe.

The Interest charges is 17.88% p.a. Wow…The guys conveniently is quoting rates per day.

I know credit card guys quote rates on a per month basis. This is on a day basis.