the planet we live on, the third planet from the sun in the solar system

ground or soil

पृथ्वी

English Usage: She dreams of traveling around the earth.

Hindi Usage: वह पृथ्वी के चारों ओर यात्रा करने का सपना देखती है।

the global human population (as in "the earth's population")

पृथ्वी की जनसंख्या

English Usage: The earth is home to approximately 7.9 billion people.

Hindi Usage: पृथ्वी पर लगभग 7.9 अरब लोग रहते हैं।