My iPhone doesn’t show its battery Health? What would be it’s problem?

Surafelabiy ~ What model of iPhone is it?...

Settings > General > About > Model Name

And what version of iOS is it running?...

Settings > General > About > Software Version

Also, has the battery been replaced?

Apple's iPhone User Guide says: "If your iPhone isn’t working as expected, you can try restarting it by turning it off, then turning it back on.":

Turn iPhone on or off - Apple Support

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Bearing in mind that the maximum capacity percentage is available on iPhone model 6 or later, perhaps your unidentified iPhone model had its battery replaced (most likeky by a local repairer without the appropriate tools to perform after the replacement).

Regards

Giulio