What do you mean by sales and purchase agreement?

A sales and purchase agreement (SPA) is a binding legal contract between two parties that obligates a transaction between a buyer and a seller. SPAs are typically used for real estate transactions, but they are found in all areas of business.sales and purchase agreement (SPA) is a binding legal contract that obligates a buyer to buy and a seller to sell a product or service.
SPAs are often used in real estate deals or when two parties are transacting a large item or a large quantity of items.
The need for an SPA forms the basis for negotiations between the buyer and the seller.

A sales agreement is a legally binding contract that allows for the sale and purchase of a property between two entities or people. These agreements are often necessary when there is no relationship of mutual trust or confidence, which may result from past transactions.
Purchasing agreements, while similar to their selling counterparts, encompass an obligation on behalf of the purchaser as well as a vendor to meet certain criteria such as quality assurance standards after the transaction has been executed. If an agreement does not have these stipulations under it then that would make it a regular sale instead of a purchase agreement.