What is this METRIC ATTRIBUTE in crashlytics

Question

I am working on an android app. I am adding custom atrributes which are integers to a crashlytics custom event. In crashlytics dashboard it is showing me some metric attribute which I don't know. For string it is events count.

code:

 Answers.getInstance().logCustom(new CustomEvent("Specific screen")
          .putCustomAttribute("userid", 1));