Opening a creator's report gives you the detail behind the headline follower count. This is the part worth spending time on before you reach out to anyone.
Audience location
Where the followers actually are. This is the single most common reason a creator who looks perfect turns out to be wrong. Someone with a large following whose audience sits in a country you do not sell to is not a fit, however good the content is.
Audience credibility
The proportion of the following that looks genuine versus suspicious. A high follower count with poor credibility is worth far less than a smaller, real one.
Engagement
How much the audience actually interacts, rather than just how many there are. Compare this against creators of a similar size rather than in isolation.
Audience demographics
Age and gender breakdown of the following, so you can check it against who you are actually trying to reach.
Notable followers and likers
Larger accounts that follow the creator, or that regularly engage with their content. Useful for a sense of the circles they move in.
Brand affinity
Which brands the creator and their audience lean toward. Handy for spotting an existing affinity with you, or with a competitor.
What it costs
For exactly what each action costs and how many credits your plan includes, see Understanding the Credit System.