Basically speaking bank deposit is lending bank money for a specific time.

Then when they get your money they lend it to somebody else at a higher interest rate than they pay you.

Typical bank deposit interest rate range from 2%-4% per year.

When they get your money they lend it for 10%-15% and make 11% and then give the rest to you.

In most countries bank deposits are insured by the government. Up to certain sum. Like 10000$.