In modern parlance, a newcomer is an immigrant or refugee who has recently settled in a new country, and who needs guidance and/or assistance to successfully integrate into their new environment. Newcomer is a welcoming word, meant to be free of the stigma of other terms.
In addition to government organizations, faith-based (religious) organizations are often quite active in the settlement and orientation of newcomers.
To older science fiction film fans, Newcomers are the Tenctonese, an alien race whose spaceship landed in the Mojave desert, and who subsequently settled in Los Angeles. Their story was told in the film Alien Nation and the follow-on TV series of the same name. As of 2016, a remake (gasp!) is reportedly in the works.
We could indulge any number of quotes that make the analogy obvious, but this one seems apropos:
You humans are very curious to us. You invite us to live among you in an atmosphere of equality that we've never known before. You give us ownership of our own lives for the first time and you ask no more of us than you do of yourselves. I hope you understand how special your world is, how unique a people you humans are. Which is why it is all the more painful and confusing to us that so few of you seem capable of living up to the ideals you set for yourselves.
Quote lifted from IMDB's Alien Nation (1988) quotes page.