If a test has face validity then it looks like a valid test to those who use it. Face validity can be compared with content validity, which describes how far the test actually measures what it aims to measure.
Example
Many public English exams have high face validity as they are seen as being very good tests by those who take them.
In the classroom
Face validity is not an objective measure of how good a test may be. However, it is as important as content validity, because learners and teachers need to think a test is credible if it is to work.
Further links:
https://www.teachingenglish.org.uk/article/evaluating-speaking-ielts-speaking-test
https://www.teachingenglish.org.uk/article/teenagers-exams-0
https://www.teachingenglish.org.uk/article/devaluating-teaching