XFP provides variables for the answer to each question on your form, which will be replaced with the customer's answer to the question.
Inserting an answer variable
When in the variable picker:
Click on the Answer tab.
Click on the relevant variable in the Response column to insert it.
Some questions, such as text fields and text areas, will offer one variable - the customer's answer. Questions such as dropdowns and radio buttons, will offer multiple variables - one for the selected label, and one for the selected value. More complex question types, such as matrices or integrated components, will offer slightly different variables.