If it comes back empty, anyone on the internet can send an email that looks like it came from you. Your clients can't tell the difference. Their inbox shows your name, your domain, your email address. But it's not you.
I scanned 5 businesses this week. 3 of them had no DMARC record. One had an email deliverability score of 20 out of 100. A CPA firm handling their clients' tax documents.
The fix takes 5 minutes. One DNS record. Your hosting provider or IT person can do it while you're on the phone with them.
Go check yours. Drop your result in the comments. I'll tell you what it means.