大名 is a polite term used to refer to someone's name, especially in formal or respectful contexts. It literally means 'big name' but is not used literally; instead, it appears in set phrases like 久仰大名 (I've long admired your name) when meeting someone for the first time. You can also use it in questions like 您的大名? (What is your name?) as a very polite way to ask.