Hi m Abdullah javed! How's it going?
I recall that you are from India. I know that English is widely known there, having once been an English colony. However, it is not a first language, is it?
You see, I mention this (as an American; and American English is very slightly different from British English) because I think it is only fair to tell you that in English, we even use the word 'understand' in at least three different ways. There are three that I know of; one for the heart and one for the mind.
1) We use the word 'understand' in the intellectual sense. Do you understand x equation, chemical formula, metaphysical concept, or something like that? For this kind of 'understanding,' the mind is called for.
2) We use 'understand' in what you might call a sentimental sense. When we ask for 'understanding' in this sense, we are not really asking someone to intellectually comprehend something. You might say that we are really asking someone to extend sympathy to us. For example: Suppose you have been with your wife for twenty years, married for eighteen. She tells you that, after your first year together, that she had gotten pregnant and had an abortion. She talks about the circumstances that drove her to make the decision and not tell you about it at the time---whatever those might be.
Now then, what she is presenting you with is not really any intellectual challenge which calls for any mental exercise. She is asking you to forgive her, to 'understand' her pain and agony; after all, she tells you, she hadn't known at the time, that you two we're "gonna be forever." Follow me? This kind of 'understanding' is clearly the province of the heart.
3) There is a third kind of 'understanding,' we call empathy. Empathy is the ability to "put yourself in the other guy's shoes." This calls for intellectual imaginative ability; but also a large dose of compassion is at least implied because the idea of putting yourself in the other guy's shoes is all about the idea of the oneness of humanity, and all that good stuff; we're talking about the combination of heart and mind with this one.