Is it seconds hand or second hand? - Watch FAQs

The hand on a watch that displays the seconds is called the seconds hand. If you are referring to used watches for sale (second-hand watches), they are second-hand watches. If it's a used timepiece that displays the seconds, it is a second-hand watch with a seconds hand.
Questions and Answers About Watches

BFG 866 seconds hand - Watch Repairs Help & Advice - Watch Repair Talk

The ultimate guide to buying used Rolex watches

What Is A Pre-Owned Luxury Watch? Timepiece conditions explained

Used Book in Good Condition

100 Years of Vintage Watches: Identification and Price Guide, 2nd Edition

Why does a Watch Need a Second Hand?, by Dyedo Tikio

UNLOCK THE JOY OF LEARNING: EasyRead's Time Teacher kids analog watch is designed to help kids learn how to tell the time in the most effective way

EasyRead Time Teacher - Teaching Watch For Kids - Boys & Girls Analog Watch - Kids Learning Watch - Learn to Tell The Time Wrist Watch For Kids - 2