### Theory:

Heat flow:
Flow of heat is the process in which energy (thermal energy) is transferred from one object to another. Generally, the heat is transferred from the hotter object to the colder object. Temperature determines the direction of heat flow.
Example:
1.  Heat transfer between a cup of tea and the hand.
When you hold a tea cup,

Man is holding a cup of tea

Would the heat energy transfer from
1. Your body to the tea, or
2. The tea to your body?
The heat will transfer from a cup of tea to a hand; because, here, the temperature of your body (hand) is lesser than the cup of tea
.
Hot object - Cup of tea
Cold object - Hand

We know that heat is transferred from a hot object to a cold object. So, In this case, Heat is transferred from tea to your body.

2. Heat transfer between air particles and the human body.

Let us assume that you are standing outside on a summer day. It is $$39$$°$$C$$ outside, would the Heat energy transfer from,
1. Your body to the air particles, or
2. The air particles to your body?
Man standing outside on a summer day

We know that the normal human body temperature is $$37$$°$$C$$. So, in this case,

Hot object - Air particles ($$39$$°$$C$$)

Cold object - Human body ($$37$$°$$C$$

Here, Heat will transfer from air particles to the human body.

3. Heat transfer between air particles and the human body.

Let us assume that you are standing outside on a winter day. It is $$24$$°$$C$$  outside. Would the heat energy transfer from,
1. Your body to the air particles, or
2.
3. The air particles to your body?
4.

Man standing outside on a winter day

We know that the normal human body temperature is $$37$$°$$C$$. So, in this case,

Hot object - Human body($$37$$°$$C$$)

Cold object -  Air particles  ($$24$$°$$C$$

Here, heat will transfer from the human body to air particles.

In the above examples, the energy is transferred from the hot object to the cold object. This energy is termed as thermal energy.

Thermal energy:
When a hot body is in contact with another a cold body, the form of energy flows from the hot body to the cold body, known as thermal energy.
Thus, thermal energy is a form of energy transferred between any two bodies due to the difference in their temperatures. Thermal energy is also known as 'heat energy' or simply 'heat'.
Reference:
https://photostockeditor.com/image/person-man-looking-at-snow-mountain-snow-69043