Non-Final Action Mailed means that the examiner has found issues with the application and outlining them in written form. Such issues can range from simple changes to the application to outright refusals for various reasons (e.g., where the application is confusingly similar to another mark already filed or registered)
The Applicant has an opportunity to either: 1) satisfy all the outstanding issues listed in the action, or 2) submit arguments refuting the examiner’s contentions or refusals.
Applicant’s generally have 6 months from the date the final refusal is mailed to respond. However, Applicant’s should review the office action itself to confirm the response deadline.
If the Applicant submits a response and fails to either: 1) address all the issues listed, or 2) persuade the examiner on any of the issues raised, the examiner in most cases will issue a final refusal.
If you have received an Office action letter, please read through it to get an idea of what you need to provide. For assistance from Trademarkia's network of attorneys, please this link.