PR到底是什么意思啊？关于出国的

PR 是 Permanent Resident 的缩写，在很多国家都可以是用。
比如 Canadian Permanent Resident，加拿大永久居民。
加拿大的永久居民卡(俗称风叶卡) 就是 Canadian Permanent Resident Card，简称 PR Card.

留学的话,是指PR (PUBLIC RELATION 即公共关系 专业?

移民方面指:澳大利亚永久居民(Australian Permanent Resident，简称P.R.)

楼上说的很详细了。
我再补充下关于移民，你要首先申请到PR，然后才能申请国籍

莫非是一个专业，如果是一个专业的话，我觉得是Public Relations 公共关系。
朗文当代英语词典

PR
n [U]
1 public relations the work of explaining to the public what an organization does, so that they will understand it and approve of it: PR agency/firm/consultant
--a large PR firm
--The band have been getting a lot of good PR recently.
--Many say it was no more than a PR exercise (=something done to make people think something is good) .
2 BrE the abbreviation of proportional representation :牛津高阶英语词典

PR
noun [U]
the abbreviation for PUBLIC RELATIONS: a PR department / agency / campaign ◆ The article is very good PR for the theatre.