You'd need to speak with someone in the state Department of Revenue for clarification. But it sounds like the DOR wants to verify your reported Gross Receipts from some portion of your tax return. Your notice from the state should explain in detail what is required. Additionally, there is likely a telephone number to call with questions.
Please contact NM DOR using that number, or the number listed in the linked info below.
In New Mexico, gross receipts are the total amount of money or value of other consideration received from:
Notice that these are not simple employer-employee relationships that would be reported on a W-2 (which the state gets a copy of), but income from other sources that are not so well tracked. See http://www.tax.newmexico.gov/Businesses/gross-receipts.aspx
The number of audits relating the gross receipts has been increasing over the last few year, as more sophisticated computer software is becoming available to cross reference database sources and find gross receipts that potentially have not been properly reported. See https://www.abqjournal.com/628699/grossreceipts-tax-audits-skyrocket-in-nm.html
Now that you have reviewed these two articles and thought about your own return, go and do what Kat says...