Last count date is the last Physical Count performed for the inventory item.  This is just to filter the item like inventory item counted 2 years ago if you want to count them this period.  You may try to create a batch to test this procedure but delete the batch immediately after testing as it may affect other transaction posting for inventory items included in your batch if you have open pending batches.

For a safe practice, you may open SOA company in your DB so you can test this in Demo environment without affecting other users in Production.  Go to File / Open company / Chose "SOA - System of America".   Using this company, you can test this inventory count procedure for you to be familiar with the process. 

Other helpful feature:  If you have questions on specific field or cell in Sage 500, just right click the field and choose "What is this?" for you to find the specifications and use of each field.  This is applicable only to field and not on this filter issue.

Thank you wilson wygonzales , that makes sense and is in line with my understanding.  Ultimately, the field is capturing the last physical count date of that inventoried item.  

The 'Last Count Date' is typically registered at the item level rather than the bin level. This means Vanilla Visa gift cards it reflects the last time the item was counted, regardless of its specific location. So, as long as the item has been processed and posted, that date should update.