Among those who translate the Bible, the term “heart language” refers to the language with which a person feels most comfortable and at ease. It is the language of his heart.
'Now there were dwelling in Jerusalem Jews, devout men from every nation under heaven. And at this sound the multitude came together, and they were bewildered, because each one was hearing them speak in his own language. And they were amazed and astonished, saying, 'Are not all these who are speaking Galilean