QQ plot explanation The figure shows the Q-Q plot of a theoretical and empirical standardized Normal distribution generated through the $qqnorm()$ function of R statistical tool.

How can I describe the right tail (top right) that does not follow the red reference line? What does it mean when there is a "trend" that running away from the line?
Thank you

It means that in the right tail, your data do not fit normal well, specifically, there are far less numbers there would be in a normal sample. If the black curved up, there would be more than in a typical  normal sample.
You can think of the black curve as a graph of a function that , if applied to your data, would make them like a normal sample.
In the following image, random sample is generated by applying Ilmari Karonen's function to normal sample.

