According to electron affinity, it is the amount of energy "released" during the addition of an electron in the valence shell of an isolated gaseous atom, and its sign convention is opposite to that of thermodynamics convention. i.e. positve for release of energy.
It is given in books that electron affinity 1 is exothermic, i.e. positive while rest all electron affinity are endothermic, i.e. negativeve.
As we already know that electron affinity is energy "released", then why we consider endothermic case under it?