Hi there, @julie-thejordang! There are two reports you can run to know your A/R days.
First, you can use the A/R Aging Detail report if you want to see a detailed A/R days of your transactions. Here's how:
Go to Business overview section, and then select Reports
In the Who owes you section, select Accounts receivable aging detail.
Enter the number of days you want to see in the Days per aging period box (see the screenshot below).
Click Run report.
Second, you can view a summary of your transactions by running the A/R Summary Aging report. For more details, you can read this article: Run an accounts receivable aging report.