Hady and Sacrifice in Hajj
Hady is the sacrifice of those performing Tamattu or Qiran (Qur'an 2:196). Ifrad pilgrims do not owe it.
The animal
A sheep or goat, or a share in a camel or cow (seven people per animal). Scholars set age and health conditions; authorised programmes arrange compliant animals.
Timing
From the 10th, after stoning Jamrat al-Aqabah; the majority extend it through the days of Tashreeq. It is recommended to eat some and give some to the poor.
If you cannot
Fast three days during Hajj and seven when you return home. Many pilgrims use official hady services; ask how and when the sacrifice is done and how you will be told, and do not cut your hair on assumption.
This differs from fidya or dam for violations; see Ihram guide.