A resident alien is an individual who is not a citizen of the country in which they reside, but they have been granted legal permission to live and work in that country. The term is commonly used in the context of immigration and legal status.
For instance, in the United States, a resident alien is an individual who holds a green card, also known as a Permanent Resident Card. This card grants them the right to live and work in the U.S. on a permanent basis, although they are not U.S. citizens. Resident aliens have certain rights and responsibilities, such as paying taxes and abiding by the laws of the country, but they may not be eligible to vote or hold certain government positions reserved for citizens.