This is the number of block events attributed to a specific site in the top-blocked-sites table. An admin uses this count to gauge whether a repeatedly blocked site represents one determined or compromised user retrying, or many different users all hitting the same link, the latter, checked via the blocked-user table, pointing to a shared source like a phishing email sent broadly. For example, a single site accumulating thousands of blocks in a day would justify checking the blocked-user table to see whether it's one persistent user or a company-wide phishing blast.