If looking for a way to add any text beginning of any field or end of the field in the mapping section. Can refer to the way below:

Once use the curly brackets and comma in the mapping section, multi columns and labels will no longer supported. 

1. Can add the text in the mapping section together with the column field name.

2. Before adding the text in the mapping section, you must ensure that the toggle shown as a tag at the top of the mapping is disabled. 

For example, 

Value in the feed file
Preferable Text that added
Field Mapping
Column name - description
Value - Length 23cm
Description: {{description}}
Description: Length 23cm
Column name - SKU
Value - ABC1234
Vendor: {{sku}}
Vendor: ABC124
Column name - title
Value - Green Leather Bag

designed in California
{{title}} designed in California
Green Leather Bag designed in California

3. There are a few fields not supported to do this which are price, compare at price, image, sales price, quantity, harmonized system code, and SKU fields. 

4. The rest of the field that is not mentioned above is able to add the text beginning of the column value or end of the value.