Many things.
1) Creating Khalsa Panth - giving sikhs an identity by introducing a phase/passage way that a Sikh can chose to go through called "Amrit Shakna" It's similar to baptisms by Christians but the individual must decide themselves whether they want to do this or not. For this reason it's not performed on babies since they can make decisions themselves yet
He also introduced the 5Ks that all Sikhs r encouraged to hold, but those who are Amritari (did the Amrit shakna) must hold.
K- Kesh- Uncut hair
K-Kirpan Small sword to stand up to injustice and protect those who need aid
K-Karra A simple steel/iron bracelet to signify the universe and connection of all individuals. A circle has no beginning or end. God has no beginning or end. A circle is always connect. The universe is always connect. Non-precious metal so everyone can afford to to emphasis contentment in simplicity
K-Kanga Comb to keep hair maintained and clean and to encourage proper hygiene
K-Kashera - Simple clean loose undergarments to also encourage hygiene but also for modesty. Simple undergarments are not flashy and do not induce lust.
2) He took on Guruship at the age of 8 after his father was martyred by the Mugal Raj. He guided the Sikhs
3) Fought injustice politically and in war against Mugals. Especially in Anandpur Sahib where his family was trapped in a fort with many other Sikhs. They were tricked into leaving as the Emperor Aurangzeb swore on the Quran he would let walk out, but he instead attacked as they left and the Guruji managed to fight and allow many to escape along with himself, but many holy pages (never rewritten) and soldiers were lost.
4) After his 4 sons and mother died in battle he and his wife settled in southern India where he spread Sikhism and help many through guidance and langar. He was assassinated here. Here there is a gurdwara called Sri Hazoor Sahib.
Guru Gobind Singh is the tenth guru of Sikhs
No, Guru Gobind Singh ji had no siblings.
Shri Guru Gobind singh ji
Guru Govind Singh
Guru Gobind Singh Children's Foundation was created in 1999.
Guru Gobind Singh Indraprastha University was created in 1998.
Guru Gobind Singh Medical College was created in 1973.
Guru Gobind Singh
Guru Gobind Singh Children's Foundation's motto is 'Children Helping Children'.
Guru Gobind Singh College of Modern Technology was created in 2002.
Because he was enlightened!
The tenth guru, guru gobind singh