There you'll find three major types of activities:
When a user you follow, or a blog you subscribe to publishes a new article, or updates a previous one, it will appear front and center, with a large preview in your feed.
When a user you follow likes an article, comments on an article, or replies to another comment, it'll also appear on your feed. You'll see a preview of the content they engaged with.
When a user you follow then follows another user, or subscribes to a blog, it'll appear on your feed, with a preview of the user or blog.
Customizing your feed
First, I have to mention: there is not, and never will be, complex algorithms that decide what you get to see first, or at all. Nor suggestions about what we think you'd like to see. That's not what I do. You get all the activity from your connections, in order, and only then you decide what you actually want to see.
Using the filter button at the top of your feed, you can easily toggle what kind of activities you want to see. Your feed will update automatically, and your new settings are saved for later.
That's about it. Simple and transparent.