Translation:It is okay!
Often the word được is used to say that someone is able to or can do something. Often positive emotions are involved.
Tôi nói được tiếng việt - I (can) speak Vietnamese (quite positive, right?)
Tôi ăn được phở. - I (can) eat Phở (yippie, finally, wuhuuuu :) )
Maybe the literal translation of cũng được would be "also can" or "can also". Because ok is often the agreement to a potential action in the near future out of a lot of other options. We can do this action (but there are probably a lot of other options, so we can do this or we 'can also' do that)
"Chúng ta nên ăn thịt chó." Cũng được.
-"We should eat dog meat." Ok (also can).
I hope this post is not too confusing. Just a little approach of an answer to this huge "ok" with a question mark. (sorry for my bad english)
Thank you for this explanation. I noticed in Vietnam a lot of Vietnamese say "Also can !" to agree. Now I understand where it comes from.
It reminds me of something else I noticed in some South-East Asian countries : when people speak english they often omit conjugating the verb and just add "last time" at the beginning or the end of the sentence to refer to something in the past. "I drive to this place, last time". It makes sense for them since their languages rely heavily on context (mostly time references and some adverbs, đã, sẽ, đang...)
Keeping that in mind helps a lot when communicating with people with limited english.
This really needs to be wide-open on what it accepts as right. What it means is "I'm ok with this/that" insofar as I can gather.
I really think that answers which include "I" should be included as this involves stating an opinion or preference and not a matter of fact. "I'm ok with this", "it's good by me", "It is ok with me", etc.