The cron expression for every 2 hours
0 */2 * * *
The minute is pinned to 0 (top of the hour); the hour step */2 selects every even hour: 00, 02, 04, …, 22. Twelve firings per day. To fire on odd hours instead, use 0 1-23/2 * * *.
See the dedicated guide for the full breakdown: Cron every hour.
Paste it into the editor above to see the next runs on a calendar.