Like a previous poster, I have found that languages-based careers are very often unsatisfying and not well rewarded. And like another, I think it's better (for many of us) to develop a primary career that your language skills can be used on top of.
I feel pure language-based careers fall into three main strands: admin/customer service-type work that requires fluency in another language, teaching and translation / interpreting. I did the first for a while and hated it, and I knew I was never cut out for the second. The third was what I aimed for for a long time, but I didn't really have the self-confidence to build up my own business. I needed a steady job, which led me back to number one...
There is a fourth area - which I think are highlighted by uni languages departments - and these are the graduates who go off and do something both language-specific, interesting and unusual. Becoming a specialist football journalist is one example I came across. These people are generally driven by a specific passion and highly motivated.
I wouldn't put your daughter off languages. I still use the languages I studied as an undergraduate and later postgraduate, and have studied others in my spare time since. It is a life-long passion for me and so I understand how enriching these studies are for your daughter.
But if she isn't very motivated towards a career in teaching or translation/interpreting or has a very specific goal in mind, it's best that she is aware that she will need to consider what route she will use to get into an interesting field on graduating. There are many. Joint honours, degree in another subject followed by a year working and studying in another country, languages degree followed by vocational qualifications, work experience while at uni, and so on. The main thing is to be aware of this now.
I miraculously thought an interesting and skilled career would just appear - when it didn't, I was stuck in the dull language-based admin roles while I made up for lost time.