Why is an increase in accounts receivable shown as a decrease in cash when computing cash flow

Question:

Why is an increase in shown as a decrease in cash when computing cash flow from operations?

Accounts Receivable
Accounts receivables are debts owed to your company, usually from sales on credit. Accounts receivable is business asset, the sum of the money owed to you by customers who haven’t paid.The standard procedure in business-to-business sales is that...