Good day, @jibim.
Allow me to suggest a report that will help you find the information you're looking for. While QuickBooks may not have the native functionality to count received vendor invoices (Bills), you can run a customized Transaction List by Vendor to display them, export the list to Excel, and use a formula to count them for you. These steps will help you accomplish this:
Export and count Bills from Vendor Transaction List
- From QuickBooks Online, navigate to the Reports tab and search for Vendor. Select Transaction List by Vendor from the pane below.
- Click Customize in the top-right. Expand the ➤ Filter menu, and check the Transaction Type box. On the drop-down, check off only Bill.
- Set the date range as This Year-to-date, and click Run Report to update the information. You can either count the Bills manually from here or continue to the next step to automate this calculation.
- Click the tiny page icon in the top-right of the report to Export to Excel. Within Excel, a special function can be used to count the bills. I used the =COUNTIF(data,"*") formula, which counts every cell in a range that contains any text. Just replace data with the column range your Amount values land in.
Here's a brief video example in which I customize the Vendor Transaction List and export it:

Using these instructions, you can quantify transaction lists like an expert. Please be sure to let me know if there's anything else you need, I'm always available here for all of your QuickBooks questions. Thanks for coming to the Community and have a wonderful rest of your day.