Verb (5-dan, ぶ, transitive)
1. to be delighted; to be glad; to be pleased; to rejoice
これは喜ぶべきことのはずだ。This is supposed to be something to rejoice over.
Verb (5-dan, ぶ, transitive)
2. to congratulate
3. to welcome (a proposal, advice, etc.); to take kindly to
彼はあまり変化を喜ばない人だ。He's not someone who really welcomes change.
Verb (5-dan, ぶ, intransitive)
4. to do with pleasure; to do gladly; to be happy (to do)
as よろこんで...
今日のような仕事なら喜んで手伝える。I would gladly help with work like today's.