I moved this as I think we need a Marketing Cloud expert to comment.
Normally the account will auto unlock after a set period. It is likely that a manual password reset will achieve an unlock also
If your organization is using Federated IDs, the number of times would be dictated by the identity provider. I'm still checking with our engineers on the number of times for Adobe IDs and Enterprise IDs. Stay tuned...
It looks like this information is not publicly available for security reasons.
As for a locked account, please have a supported user contact customer care with the locked user's email address.