How to merge Contacts into a Numbers spreadsheet?

Start here:

Import or export a vCard in Contacts on iCloud.com - Apple Support

You should be able to convert the vCard file into a CSV file that Number can read.

If you're using Excel see here:

How to Open VCF File in Excel? – Manually

1. Open MS Excel sheet.
2. And click on the File tab or select the “Office” icon.
3. Now click on the “Open” tab from the list and hit on the “Browse” icon.
4. After that, search your VCF file and select it.
5. Now “Text Import Wizard” will open, and here choose the “Delimited” option.
6. And hit on the “Next” button to continue the process.
7. Now add the delimiters as ‘Tab’, and “semicolon” and then select “Other’ delimiter & type ‘:’ in the field.
8. Lastly, hit the “Finish” icon to open the VCF file in Excel.

Thank you, IdrisSeabright.

I'm using Numbers, not Excel. However, I did not find a menu or menu item for Import. It's been a while since I have imported anything into Numbers and a lot of things got moved around in a recent (in the last year) iWork update. I'm sure that there used to be an Import menu in Numbers. Can you tell me how to find it. Thanks! Jack

You might take a look at this section of the manual:

Import an Excel or text file into Numbers on Mac - Apple Support

Look at the section on text files.

I would like to ask a follow-up question: How would I convert the vcf file into a CSV file?

Thank you. Jack