As a Verb or Adjective:
1. To appear to be reasonable, correct or just considering the circumstances or evidence. English = (be) fair.
2. To be neither very good or very bad and to be suitable or normal for the occasion. English = (be) acceptable, (be) average.
3. To look like or appear to be. English = seem.
As Modifier:
1. Used to introduce a judgement which is contrary to a previously expressed one and which you hope helps to balance the general picture. English = 'To be fair.'
2. Used to introduce a sentence to mean you think that what follows is true but you are not completely sure. English = apparently, seemingly.