Business is considered to be an economic activity as the sole purpose of starting a business is for earning profit. For example, grocery shops, medical shops, vegetable shops, are the business.
The profession includes activities, that require special knowledge and skills which individuals can apply in their occupation. Examples are doctors, engineers, architects, etc.
Employment is the occupation done for others and gets paid for it. The employed individuals are called employees and the organisation who gives employment are called employers. Examples are Managers, team leaders, sales executives, etc.