The file you're referring to, is a collection of stolen or leaked email addresses and passwords. These lists are primarily used by cybercriminals to gain unauthorized access to online accounts. What is a Combo List?

Combolists and ULP Files on the Dark Web: A Secondary ... - Group-IB

Downloading or attempting to use these lists is and poses significant security risks to you:

: They are typically compiled from previous data breaches, phishing attacks, or malware like "infostealers" that grab login info directly from a victim's device.