What is a Data Feed?
A product data feed is a way of sending structured, current, machine readable and up-to-date product information. This is a way of exchanging information between platforms / systems etc.
Data feed can be implemented in different formats. Most common formats of data feed are XML, TXT, CSV etc. However, product data feed can also be made with a help of API.
Do i need a data feed? To be short - not necessary. But if you want to import products into WiseXML then data feed is one of the ways to do it.