What do this data mean please?
The entry in question is for δ Orionis.
"A = 2" means the primary component was estimated at apparent magnitude 2.
"1879,12" is an observation date in fractional years, using a comma as a decimal point.
"163,0" and "161,7" are position angles from the primary component to the secondary, in degrees counterclockwise from celestial north. The * indicates an observation by Stuyvaert instead of Niesten. "162,35" is an average of the two observations.
"en contact" means the separation between the two was smaller than the telescope's angular resolution. Otherwise their separation would be given in arcseconds.