I have someone willing to work on getmonero.org to translate into portuguese, was wondering if getmonero.org have some language system already build or how he should address the translation
I'm not entirely sure how the translations are being handled, but I recommend going to the official Monero forum and maybe posting it in the 'Ideas' section and seeing what the response is.
That being said, I have read once or twice about someone wanting to redesign the website. So if that is the case then it may be better to wait.
Or if you want a more immediate answer you can try the #monero or #monero-dev channel on Freenode.
I'm not sure what the procedure is, or if there is any procedure, but you'll want to start by translating the file https://github.com/monero-project/monero-site/blob/master/_strings_en.yml
This file contains the menu strings and the text on the homepage. For Portuguese, you'd create a copy called _strings_pt.yml. And then you'd have to ask the devs to include your language in the language selector. But at the moment, the site is monolingual. Translating other pages, like the Getting Started section, may be more complicated.