The Fourth house is one of the four Kendra or Quadrant houses in astrology. It is also known as 'Sukha Bhava' i.e. House of Peace and 'Bandhu Bhava' i.e. House of Relatives. It represents a wide range of areas in one's life, mainly mind and heart peace and domestic happiness.

It primarily indicates Mother and motherland. Family members and relatives who can be well-wisher in your life. Home and its environment. Comforts and pleasures derived from the land and ancestral property as well. It represents the fixed assets and cattle- sheep, goats, buffaloes, etc one owns. 

Another important aspect governed by this house is the quantity and quality of vehicles one owns. One's character, good fame and virtues, spiritual inclination, faith to the almighty, family history, traditions, cultures and how well one adapts to societal norms can also be seen from this house. One's material gains and all sorts of tangible wealth including possession of jewels can be seen from the house.
In brief, emotional satisfaction along with material contentment.

It is also one of the important houses to be observed along with 8th and 12th house for matters concerning to attainment of Moksha(salvation). Hence, it not only governs the origin(mother) but also our final resting place, the sole mother of the entire mankind i.e. the Mother Earth. This is how the fourth house is the representation of the complete life cycle and even beyond (salvation).

According to Hora, 

"The 4th house is called Hibuka, Sukha (happiness), Yesma (residence), Pathala (underworld), Vari (water) and Bandhu (relatives)."

Change of residence, how well your roots (domestic land) suits you, wells, water, milk, treasures, mining, your relationship with mother, the nourishment and care one receives from mother and your possessions of all material gains along with property and vehicles - all come under the domain of the 4th house.

Since it is fourth (Cancer sign) in the series, the natural ruler of this house is the Moon. The planet Venus is also the natural significator of this house along with Moon.

Body parts ruled are the chest, lungs, breast (as it represents nourishment and love of a mother), heart, circulatory system, stomach, etc.

You may refer to:

https://www.thehailphoenix.com/2019/11/the-birth-chart-part-2-planets-and-sign.html?m=1


Stay happy and blessed!!

XOXO...