This feature on the Twitter platform has 5 functions: Tweets, Activity, Who to Follow, Find Friends and Popular accounts.
The Tweets option shows the most popular Tweets across Twitter; some are tailored to you individually and some are globally trending.
The Activity tab shows notable engagements of the people you follow, including the latest retweets, replies and favorites of your friends.
Who to Follow helps you find new and interesting accounts.
Find Friends allows you to import contacts from your contact book and find them on Twitter.
Popular Accounts provides a list of some engaging and well-liked accounts on Twitter and is delivered to you based on your interests.