The triangle flag with orange field and blue symbol is the flag of the Sikh religion.
A minor quibble, I would consider it highly probable the orange would be saffron, it being the colour used by Khalistan supporters for their turbans as a sign of protest.
The saffron triangle flag of the Sikh religion is called a 'nishan sahib' and can be seen flying above any gurdwara (Sikh temple) - 'nishan' means 'mark' or 'flag' and 'sahib' is a term of reverence. The mast that bears the flag is covered in saffron or dark blue cloth at all times.
This web page provides an extensive PDF document detailing, among other things, the proper way in which to display or process with the 'nishan sahib' and occasions which warrant the hoisting of the flag, brief construction details, symbolism, history, and the importance of the flag to the Sikh community.
The color of Sikh flags, described as saffron, actually is usually light orange, also known as "deep saffron", but may also be saffron proper, which is a dark shade of yellow [Wikipedia]. A photo showing flags of both colors together can be seen at The color of the symbol is usually blue, but may be black as well. As the photos available on the Web can also show, there is no fixed aspect ratio and the flag shape may be either isosceles or right triangle, although the latter is preferred.