Digital fluency is the understanding of technology and its uses. Students can show digital fluency by making good decision when using technology and not using technology for hurtful reasons.
Below are some websites that further explain digital fluency.
https://www.digitallearningcollab.com/blog/what-is-digital-fluency
https://study.com/academy/lesson/what-is-digital-fluency-definition-example.html
http://blog.core-ed.org/blog/2015/10/what-is-digital-fluency.html