Net profit is also called net earnings or net income. To fully understand this KPI we need to understand the income statement and some of the accounts on it. Investopedia says that the net income is a formula that is sales minus cost of goods sold, selling, general and administrative expenses, operating expenses, depreciation, interest, taxes, and other expenses. The data is collected from an income statement (also known as a profit and loss statement or a P & L statement). Here is the formula.
This will be expressed in a particular currency, such as dollars or pounds. Net profit is usually measured each month.
For more information, The Main KPI Types has a list of some KPIs and their types.