The Posts Performance tab, as the name hints, will show you the performance of your posts in terms of interaction. This way you'll be able to learn what kind of content your audience likes best! and adjust your strategy accordingly!
Reach: The number of people who saw any of your posts at least once.
Reach by post type: Average number of people who saw any of your posts, at least once, grouped by type of post.
Reach by time of day: Average number of people who saw any of your posts at least once, grouped by time of day.
Reach by weekdays: The average number of people who saw any of your posts grouped by weekdays.
Engagement by type of post: The number of times people engaged with your posts through reactions, comments, shares, and clicks, grouped by type of post.
Top Posts: Posts that got more engagement.
Recent Posts: The most recently published posts on your page.