Having a table with several colums that should be transposed to rows, the row normaliser step can be used:

Type field: can be anything

Fieldname: Here put the colum header names

Type: can be anything

new field: this will be the field where the value of the column will be transposed.

Result:

Note, that fields, which are not added in the rows normaliser step as fields, will simply be added to the output without normalization.