Please elaborate what does it mean by soft skill in term of English language.
From Wiktionary a "soft skill" is
Contrast this with a "hard skill":
Soft skills are those needed when dealing with people and emotions which are "soft" when compared with technical things which are "hard".
Also, "soft vs hard" does not refer to difficulty. In fact the soft skills are often more difficult to acquire (i.e. "harder") than hard skills.
The sexist among us might say that women are naturally better at soft skills while men favor hard skills. This "observation" is the basis for many sitcoms. Indeed much of the humor in the show "Bones" comes from the tough (male) FBI agent having far better soft skills than the detached (female) scientist.