Question about combolists

Hello everyone.
I bought a hacking program, and there is a combolist maker inside.
It requires me to upload a passwordlist and fill in the (for example) IG username.
After that, I get a txt file with the username:password structure.

This is the part I totally understand.

But when I download email:pass combolist (on this forum for instance)
Its a text file with a lot of random emails and random passwords.
Are those passwords connected to the emails?
If I put that in a crackingtool, what does it exactly do?

Thanks in advance

well anyone correct me if im wrong but as far as I know if the email.txt is set up like this [email protected]:123456 then u load that text file wich is your combolist into cracking program and it runs threw all accounts untill it gets a hit in the program.

The tool checks if the leaked email:pass combo works with the site or program u set it up for
If u have a password list and only one username it will try the username with all the passwords

Are those passwords connected to the emails?
Yes, email and password was extract from database of websites, for example dropbox.com. Because people kind of use same password for all accounts the combo will work for other sites.
All the tool do is test the combo to find if it work on your wanted site or not.

That is a combo list, you can use a cracker or the tool that you bought so you can check that email: pass and see if you have any hit