Understanding parts of speech is extremely important for developing a correct sense of word order.
Literal
Parts-of-speech [object-を] understanding [topic-は], correct word-order sense [object-を] acquiring [purpose-うえで] extremely important thing [copula-です].
品詞 (ひんし, 'parts of speech') and 語順 (ごじゅん, 'word order') are linguistics terms. 正しい語順感覚を身につける ('to acquire a correct sense of word order') uses 身につける ('to acquire / to learn,' literally 'to attach to one's body'). ~うえで ('in / for the purpose of / when it comes to') marks the context or purpose. 非常に大切 ('extremely important') is the formal intensifier 非常に + 大切. An educational-register sentence about language learning methodology.