Revenue is the total amount of income generated from the sale of company products, e.g. Apple earns revenue from selling MacBooks and iPhones.
Formula: Revenue=Number of sales X Sales price
Expenses is the cost generated from the purchase of a product or commodity, e.g. Apple needs to pay rent for their land and buildings, that rent will be recorded as an expense, Apple needs to pay their employees, the employees wage and salary is an expense incurred by Apple.
Profit is the financial gain earned by a company, e.g. Apple sells an iPhone costing them $1000 for $1300, they make a Profit of $300.
Formula: Profit=Total Revenue - Total Expenses