In Sanskrit, linga means an emblem, an insignia, a mark, or an indication. One may wonder why this Subtle Body is known as a linga, or an indication, or a mark. It is because whatever the sukshma-sarira or the Subtle Body is, that man is. It is an indication of what man is made of. The physical body, or the physical feature, or the physiognomy of the body, is also an expression of the internal composition of the Subtle Body.
Electricity is there inside physical matter.
Something like that, one may say, is the way in which the Subtle Body is inside the physical body. The Subtle Body is a force. It can be compared to electric energy to some extent. It is not a hard substance. Just as the physical body is made up of the subtle essence of the food that the parents have taken, and also the food that one eats, the Subtle Body is constituted of many other small components.