Import list of abbreviated months

I’m trying to import a list of month abbreviations such as:
“Feb,Oct,Nov”

When I export this type of data from a custom field I created in S2memberPro, I get this very odd string:
“a:3:{i:0;s:3:“Feb”;i:1;s:3:“Oct”;i:2;s:3:“Nov”;}”

What does this additional data mean, and can I ignore when importing a CSV?

Well, where you try to import that list? And why? How you will use it?