Core Cash Target is the ideal amount you will have in your bank account before spending on new projects, paying shareholders, hiring new team members etc. It's calculated by adding your taxes due and two months worth of overheads for the current period.
If you select a finalised month (see red square above) that isn't the financial year end then the figures will be annualised for the current financial period.
The little coloured number in the lefthand corner is the amount difference in the core cash target between now and the previous financial year.