As Vic posted, it blocks the hammer .
Some years ago I bought my first 1895 and I dropped the hammer on a nice cow and heard "CLICK" ,not boom. What the...
The safety had done it's job but the cow was gone...
I redeemed myself 10 minutes later on another cow and have since "fixed" these safeties on several 1895s with a small "o" ring in the groove of the safety to keep it in the Fire position.
I much prefer the Half-Cock position of the hammer as a safety.

They are great rifles but getting familiar with something new and different is best done at home and on the range.
Good luck!

"Camping places fix themselves in your mind as if you had spent long periods of your life in them.
You will remember a curve of your wagon track in the grass of the plain like the features of a friend."
Isak Dinesen