What have you tried to do with those data?

I have data at several points downstream from the grid. In that excel sheet I only have provided velocity signal data of two points.

I just want to calculate integral length scale from the two point correlation function and the turbulent dissipation rate.

@Filippo Maria Denaro 

But do you know how to do that first from a theoretical point of view?

This is quite a classical topic in the statistical analysis of turbulence. For homogeneous isotropic turbulence, the integral scale can be associated to the Taylor microscale lambda. That can be computed from the autocorrelation, as explained in many textbooks (e.g., Pope).

You can find a lot of link searching in the web, for example

http://www.seas.harvard.edu/brenner/taylor/handouts/taylor_stats/node3.html

https://www.io-warnemuende.de/tl_files/staff/burchard/pdf/Turb_Chap4_WS08.pdf

Thank you sir @ Filippo maria Denaro