A more thorough explanation:

A reservation is a legal term that can have two different meanings:

1. When a property owner sells their property, they may include a reservation in the deed. This reservation creates a new right or interest for the property owner in the property they just sold. For example, if a property owner sells a piece of land that has a private road running through it, they may include a reservation in the deed that allows them to continue using the road. This means that even though they sold the land, they still have the right to use the road.
2. A reservation can also refer to lands that are under the jurisdiction of federally recognized American Indian tribes. This includes Indian reservations, public domain Indian allotments, former Indian reservations in Oklahoma, and land held by incorporated Native groups, regional corporations, and village corporations under the provisions of the Alaska Native Claims Settlement Act.

For example, let's say that John owns a piece of land that has a river running through it. He decides to sell the land to Sarah, but he wants to make sure that he can still use the river for fishing. So, he includes a reservation in the deed that gives him the right to use the river for fishing even though he no longer owns the land. This reservation allows John to continue using the river even though he sold the land to Sarah.

Another example of a reservation is the Navajo Nation Reservation in Arizona, New Mexico, and Utah. This reservation is home to the Navajo people and is under their jurisdiction. The reservation covers over 27,000 square miles and is the largest reservation in the United States. This reservation is an example of land that is under the jurisdiction of a federally recognized American Indian tribe.