A writing sample is a supplemental document for a job application often requested for jobs that include a significant amount of writing, like those in journalism, marketing, public relations and research.

Has written meaning?

Has written. Has been writing. And note that. if you want to express that you have completed some work in past time you use past indefinite. If you want to express that you have completed some of your work in past (that means you have some result) you can use present perfect.

Was written is written?

Was written is past tense. Was the writing done in the past? If so, then “was written” is correct; if not, not. (It could have been spoken rather than written.