Link the content of a column with Data Validation to populate the adjoining column?

Hi, I have created a spreadsheet and I have two columns that I want to link if possible.

I'm not great with Excel by the way.

In column one I have a list of document numbers and in column two I have a list of the corresponding names.

I want to be able to click on the document number in column one and have the second column automatically populated with the name of that document.

Is this possible please?

I would be grateful for any help.