Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
marvellously is an adverb meaning "(used as an intensifier) extremely well". It carries one recorded sense.
(used as an intensifier) extremely well
“her voice is superbly disciplined”
“the colors changed wondrously slowly”
intensifier
Definitions, synonyms and semantic relations for marvellously come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.