with HR people it's hard to know just what they mean...
"share an approach" could be taken as implying they would expect you to take a lead on this, do training and generally spread best practice* among other staff / volunteers and so on - or did they mean 'show' (as in have done it before?)
presume there's data about service users / clients as well as volunteers?
google sheets seems to be an online alternative to excel -
Google Sheets: Free Online Spreadsheets for Personal Use - never handled it but would expect some of the commands to be different / buttons in different places to excel (i use libre office at home which is broadly similar but sometimes annoyingly different.) may be worth having a play (seems to need a google account) with it.
if they use database packages you've not used before, then may be worth selling times that you have learned a new package.
* - i mis-typed "beast practice" at first. which probably isn't the same thing...