The “Nishan Sahib” is the Sikh flag. The Nishan Sahib identifies the location of a Gurdwara (Sikh temple). 

The Sikh flag was conceived of by Guru Nanak Dev Ji, the first Sikh Guru. Traditionally, this flag has a yellow/orange triangular shape, and bears the Adi Shakti symbol, representing the primal force of God. 

~ Living Reality (1994) by Bibiji Inderjit Kaur Khalsa.