In sociolinguistics, what is meant by language rights?

To scholars of sociolinguistics, language rights are a
subset of human rights.  In other words, just as we have the right to our life and our
liberty, we also have the right to our language.  Language rights is the idea that we
have the right to speak our own language and to have that language be
respected.

The idea behind this is that, scholars say,
people usually think it is okay to discriminate against people based on language.  It is
acceptable to look down on someone who does not speak the dominant language of a country
properly and with a good accent. As one of the links
says:

• Linguistic differences are associated
  w/class, religious, gender, ethnic etc. differences.
  


• Discrimination on the latter grounds is no longer
  publicly acceptable, but


• Discrimination on the grounds
  of accent, dialect, etc. is tolerated.
  


• If attitudes to language stand for attitudes to
  speakers, then it follows that:


• Discrimination on the
  grounds of language use stands in as a proxy for discrimination on social grounds, and
  naturalizes and legitimizes it.


• I.e. one can openly
  discriminate against lower-class, foreign or ethnic students, job candidates, etc. by
  means of language discrimination, while avoiding direct (and possibly illegal) reference
  to class, ethnicity, or nationality.

Language
rights activists argue that the right to be free from this sort of discrimination is a
fundamental human right.  They believe that people should not be allowed to discriminate
against others on the basis of their linguistic heritage.  The UNESCO link is to a
declaration of universal linguistic rights -- it should help you understand what rights
these scholars think should be protected.