The four Beej mantras that constitute to become the Leo (Singh) Rashi Beej mantra are as follows.
Om: ॐ
Om is considered the most mystical sound of the universe. The ancient Indian scriptures, the Vedas, consider it to be the sound of the universe.
The sound Om consists of three fundamental sounds: A, U, M.
Om is considered a holy sound in Hinduism and Buddhism.
In Hinduism, it represents the Trimurti, a merger of Brahma: the creator, Vishnu: the sustainer, and Mahesh (Shiva): the destroyer.
The sound Om is also believed to encompass all of existence: what was, what is, and what will be.
It evokes a sense of completion. Om also symbolizes the three Vedas: Rigveda, Samveda, Yajurveda.
Hreem/Hreeng/Hrim: ह्रीं
The Hreem Beej mantra is a salutation for Goddess Bhuvaneshwari or Mahamaya.
This beej mantra is very powerful as it attracts leadership qualities in the person who chants it.
This mantra is known to provide help in tough situations and invite good fortune.
The Hreem mantra is composed of four root sounds. The Ha sound represents Shiva.
The Ra sound represents Prakriti or nature. Prakriti is also represented by Goddess Parvati in ancient scriptures.
The 'ee' sound represents Mahamaya. The 'm' at the end is to invoke the power of dispelling sorrow.
Shreem/Shreeng/Shrim: श्रीं
The Shreem Beej mantra is a salutation to Mahalakshmi, the Goddess of wealth and prosperity.
It is recited for achieving success in business, for wealth or material gains, for the elimination of doubt and illnesses, and for protection from evil.
Shreem is composed of three sounds: Sha, Ra, eem. Sha represents Mahalakshmi, Ra means wealth, and ee represents Mahamaya or satisfaction.
And the end sound of 'm' dispels all sorrow.
Sauh: सौः
The Sauh Beej mantra is also known as the hridayabeej (seed of the heart) and amrutbeej (seed of the elixir).
The Sauh mantra is composed of three sounds: Sa, Uu, and Ah. According to Vedic texts, the Sauh Beej mantra becomes competent for initiation leading to liberation without any sacrificial rites.
That is why many mantras end with this Beej mantra. It is known for being the final liberation where nirvana and emancipation meet.
The Sauh mantra, also known as Svaha, is also considered the cosmic pulsation of the supreme power. In some context it also invokes your true self translating to "I am".