It says Entfernungsschätz-Buch, actually.
It's for documenting a soldier's training in estimating distances. This one was used for training in 1908; the soldier in question was Musketier von Eigen of the 2nd company of the 2. Ermlandisches Infanterie-Regiment No. 151.
The column headings are:
"day - target - estimate in meters - actual distance in meters - error - error in percent"
"total of the percentages - average of the percentages"
where would we be if we did not have people like you HPL and F-B.