This is a charge for the Amazon.com Cloud Drive storage. Mine was automatically charged to me as a pending transaction just because I paid to become an Amazon Prime customer. Apparently, the cloud storage was a free benefit last year and Amazon wants to charge me for another year. That is, charge me without explicitly asking me first.
This is a very shady tactic, at best.
Amazon's Customere Service can be reached at 866-216-1072 (in Washington state). The first service rep transfered me to the "Cloud Storage" department where that rep deleted the charge.