Question

What do you mean by electo gain enthalpy

Answer 1

means that energy needs to be supplied so that the electron can enter the atom
but if the electron gain enthalpy is negative then it means that energy is released by the atom while taking in the electron.

hope this helps

Answer 2

the energy which is required to remove an electron from an outer most orbit shell is known as electro gain enthalpy
enthalpy is the form of energy related to electrochemistry