With this as an example of a Data.dat data file:
1 10
2 20
3 15
4 16
5 19
6 5
You can run this script to display the fields and the corresponding value of this window above it:
set key off
plot 'Data.dat' with boxes fill pattern 1, '' u 1:($2 + 0.5):($2) with labels
, u 1: ($ 2 + 0,5): ($ 2), 0.5 , .