Within the item record, Koha displays the total for Current Renewals.  This total is actually the total number of renewals ever on this item, so the description is a little misleading.  Whether the item is currently checked out or not, the Current Renewals will display a count.

There is a bug related to this issue on Bugzilla, details of which can be found here: https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=6271

However, when you are aware that the description is a little misleading, this is a useful statistic.