It is one of Parvati's names. Parvati has many names, such as - Parvati being daughter of the mountain. The synonym of mountain is शैल, so being the daughter of शैल, she is called शैलजा, also. As she became a "Sati" in the Yajna performed by her father Daksh, she is called सती also. Having fair complexion, she is known as गौरी. In her previous birth, she was daughter of Daksh. Then she became a सती and was born as the daughter of mountain so she began to be known as पार्वती. The another name of पार्वती is उमा. With an intense desire to marry Lord Shiva, Parvati was ready to start severe penance, then her mother Parvati tried to stop her, saying - उ = O daughter!" मा = Don't (means-don't perform such severe penance. उमा = Don't do that. This is how, पार्वती came to be known as उमा.