Wow, that is a lot of email addresses and passwords.
Let's start with the raw numbers because that's the headline, then I'll drill down into where it's from and what it's composed of. Collection #1 is a set of email addresses and passwords totalling 2,692,818,238 rows. It's made up of many different individual data breaches from literally thousands of different sources. The unique email addresses totalled 772,904,991