Simple Definition:

Trade is the exchange of goods or services between people, countries, or businesses [goods: physical items; services: non-physical tasks or work]. This can be done locally or internationally, and involves buying and selling products or services for money or other items of value [value: something that is considered useful or important]. For example, a farmer might trade their crops with a local market for money, or a business might trade their products with another business in a different country to expand their market.

Very Simple Definition:

Trade is when people buy and sell things with each other. This can be done in different places, like in a store or between different countries. For example, if someone has extra apples and someone else wants them, they might trade the apples for something else they need.