Access is basically a flexible database tool. So, for marketing/sales, etc., it could be used as a database to store contacts, client data, etc.
It is not as intuitive as some of the other Microsoft tools, in my opinion, and takes a bit of getting used to, as it's not "plug and play". That is, you have to learn some very basic things in order to "build" the template to show how you want each record to display.
As an example, my company uses an Access database to hold information about all of our 350 locations around the country. So, when I want to know a store's address, phone number, opening date, other comments entered by my colleagues, etc., I type the "store number" (in this case) into a field and it instantly pulls up the record with the data I am looking for. Access also allows you to build reports. Again, that feature is very flexible (you can even export the reports into Excel format if you want), but it takes some getting used to.
I hope this helps! :-)