Use reputable tools like Have I Been Pwned to see if your email address was part of this or subsequent larger Yahoo breaches.
A group known as D33Ds Company claimed responsibility for the breach. 418.6K_PRIVATE_Yahoo.txt
If you are researching this file for personal security or academic reasons, here are the steps generally recommended to mitigate risks from such leaks: Use reputable tools like Have I Been Pwned
Activate Multi-Factor Authentication (MFA) on your Yahoo account and all other critical services. complex passwords for every site.
Ensure you are no longer using any password that may have been in that 2012 file. Transition to a reputable password manager to generate unique, complex passwords for every site.