Hi, Yeji! To "put a dent in" something is an idiomatic expression that means to reduce the amount of something or to consume something. In your example, to "put a dent in" a bank account means to noticeably reduce the amount of money in the bank because the cost of whatever it is you're trying to purchase is too much. Since it won't put a dent in your bank account, this means the price isn't too high. I hope this helps. Please let me know if my answer is confusing. Idioms can be difficult to explain sometimes...

Hello: In a world where prices are rising faster than pay --> payments/salaries. (The) so called millennials, the generation that came of age after the 2008 financial crisis, are their core customers. ---- It won't put too much of a dent to your bank account means that the product which is going to be bought is not very expensive, i.e. it will cause very little "harm" financially-wise. Hope this helps :-)

A dent in your bank account means paying an amount of money. The metaphor is that a children's bank account is a piggy bank. When you need to get money out of it the thought was that you would have to smash it to get your money back out. A dent being another word for damage. The piggy bank wouldn't be hurt to bad by the amount of money you would need to get out to pay for the item.