An Application Password lets services like Storipress use your WordPress account safely. Storipress needs this password to sync your articles.
How to enable Application Passwords
Storipress’ WordPress plugin uses an Application Password to connect to your WordPress instance. If you use the Wordfence Security tool, here's how to turn on Application Passwords:
FAQ
Will turning this on make my WordPress less safe?
No. WordFence turns off application passwords because bad websites can trick people into giving away an Application Password. To reduce this risk, Wordfence, by default, turns off Application Passwords. Learn more about it here. As a side note — every Google account in the world uses Application passwords to secure connections from your account to apps (so it's pretty secure).
Can I turn off Application Passwords after connecting Storipress?
No, Storipress always needs your Application Password to connect to your WordPress account.