This means the review team didn't reach a clear decision during the 1st review, which usually happens if your content is close to not meeting our policies. Take another look at YPP Policies & you can use this time to make updates. More here: https://yt.be/help/YPP-review
After making changes to your content, the next step is to reapply in 30 days from the date you received your email. This will send your channel along to the YPP team for a new review. Our team isn’t able to get your application reviewed faster, thanks for understanding!