Ger toshav is a Hebrew term that refers to a non-Jewish person who lives in the land of Israel and observes the seven Noachide laws. These laws are basic ethical principles which include the prohibition of idolatry, blasphemy, murder, theft, forbidden sexual relations, eating the flesh of a living animal, and establishing courts of justice.
Think of these laws as a set of rules that everyone, regardless of their religion or beliefs, must follow to live in society. Just like you have to follow rules at home, school or in your community to keep things running smoothly, the seven Noachide laws are necessary in any society to maintain peace and order.
Someone who follows these laws and lives in Israel is considered a ger toshav. They are seen as a welcomed member of the community and are entitled to certain rights and privileges, such as protection under the law, the ability to purchase and own land, and to trade freely.
In essence, ger toshav is a way for non-Jewish people to live in Israel and be recognized as a valuable member of society, as long as they follow the basic ethical principles.