If you are an inventory based business then you will at some point need to count inventory. There are a number of business strategies on how to approaching counting depending on the nature of the products. For example high turn over products you might want to count more frequently then low turn-over products. Once you have you strategy worked out then you can setup a counting journal and use different means to filter and look for the items you want to count. The counting journal in AX just gives you a mechanism to record the result of a count.
Here is a quick overview.
AX2012 R3 CU11