Like a social media site, you can have a profile to tell other people about yourself. You can make new friends or connect with old ones, join groups, and participate in discussions. You can also see what your friends are currently reading and what they have previously read, as well as their ratings and reviews for different books.
Some other nice features include setting a goal for how many books you wish to read for the year, and the ability to search for new books that you may enjoy. Sometimes, authors offer ARC copies of their book to Goodreads users before the book is actually released. Keep your eyes peeled for those, and you can read the latest and the greatest before they're even available to the public!
If you'd like, you can send me a friend request at my Goodreads account. I hope to see you there!