Vendor is defining as supplier of goods or services. Normally, a vendor will sells the products or services to another company or individual. Vendor Field also provided in field mapping. 
For this part also provided some settings over there such as :

1. Append Prefix / Postfix on Feed

Append the prefix / postfix on feed will let you to add some wording that you want to be added or updated for the product. Its support with characters and symbols. 

For example:

A. Adding SKU: as Prefix in the vendor field


Value in feedResult
CB34575
SKU: CB34575
AB645856SKU: AB645856
NikeSKU: Nike


B. Adding Collections as Postfix in the vendor field


Value in feedResult
XES
XES Collections
AdidasAdidas Collections
NikeNike Collections



2. Ignore Words

Ignore words lets you ignore the specific wording that you don't want to be added or updated for the product. Its supports multiple ignored words, separated by a comma while its also support regular expressions too.