What is the intended meaning of hijrah (migration) in the hadeeth “The best immigrant is the one who immigrates from what Allah the Most High has prohibited” [1]?

This hadeeth uses the practical act, the act of hijrah and brings out the metaphorical understanding from that act. We generally understand the concept of hijrah as being migration. When most people think of hijrah, they think of it as migrating from a western country to a Muslim country, but actually hijrah doesn’t necessarily mean leaving a country. It could mean leaving a region or a part of the city to another part of the city where one can practice Islam more comfortably. The meaning of hijrah in this hadeeth is to migrate from an area where one has difficulty in practicing Islam to another area where one could practice Islam better. It is to move from that area where you are uncomfortable in practicing your Islam to an area where you are more comfortable for yourself and your children. That is hijrah. So, hijrah doesn’t necessarily mean leaving one's country and going to another but the general principle is about practicing Islam. The principle and purpose behind migration is to able to practice Islam better and wholeheartedly.

Reference:

[1] [Sahih Bukhari Hadeeth:10, Sahih Muslim, Hadeeth: 41]