I received a message stating “TAKE ACTION” With the tax topic code 151 appeal Your Rights. What does this mean?????

What was the outcome of your situation?  

This message means your return is under review for an unknown reason. The IRS will be sending you a letter about this, generally asking for proof of income or deductions. Wait for the letter to arrive.

See TurboTaxDavidD' answer below for reference.

https://ttlc.intuit.com/questions/3676700-the-irs-says-take-action-tax-topic-151-your-appeal-rights

I recieve