You can use the 'plot over a line' filter and in the properties, click on x-axis. Then you can enter the x-coordinate of the line that you wish be plotted on. If you scroll down, you'll see the options to choose the variables to be plotted. Select U and kappa to plot the velocity and turbulent kinetic energy respectively, and click on Apply. Your plot should appear on the right side in the ParaView window.

Regards,
Ashley

The current tutorial, Basic-Post-Processing-using-ParaView, is based on the earlier tutorial, Simulating Hagen-Poiseuille flow through a pipe, which is a laminar flow. You can try plotting the k (kappa) plot in the subsequent turbulent tutorials.