1. light; well-lit; well-lighted
2. bright (of a colour); brightly-coloured; brightly-colored
3. cheerful; bright; spirited; sunny (e.g. disposition)
4. encouraging (for the future of a project, etc.); promising; of fair prospects
5. familiar (with); knowledgeable (about); well versed (in)
as 〜に明るい
6. fair (e.g. politics); clean; impartial