It's displayed by default. Once you set cue points, you will see the bar count display the number of bars between each cue point.
Cue points are different from Hot Cues. When creating CUE POINTS you must make sure you have the MEMORY panel engaged on the sub-panel of the deck you are working on. See image.

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For more detailed information, refer to the Rekordbox manual: https://rekordbox.com/en/support/manual.php