I was able to see the types of cables ("* TYPE " in my data table) entered manually and the length of these cables (automatically calculated using the " Slength *" function with the name LONG in the field calculator). this whole info on the same label
("*TYPE||'\n'||LONG||'m'*").
It is now impossible to make visible the orientation of the cables (Shape of line type) in gradians (between 0 and 400), with the origin reference in the Eastern direction.
To get line angle you can use field calculator depending what exactly you need: - line_interpolate_angle(geometry,distance) - angle_at_vertex(geometry,vertex)
For more details check help in field calculator: 
Result is in degrees (north origin), to convert it in grads you need to multiply by (400/360).
So field calculator expression would be something like: line_interpolate_angle($geometry,0) * (400 / 360).
Since you need angle originating from east you will need to add 90°: (line_interpolate_angle($geometry,0)+90 )* (400 / 360) and substract 400 for features that have value above 400g.
