light ; well-lit ; well-lighted

bright (of a colour) ; brightly-coloured ; brightly-colored​

cheerful ; bright ; spirited ; sunny (e.g. disposition)

encouraging (for the future of a project, etc.) ; promising ; of fair prospects​

familiar (with) ; knowledgeable (about) ; well versed (in)

fair (e.g. politics) ; clean ; impartial

wikipedia 明るい

weblio 明るい

kotobank 明るい

jisho 明るい