Since: 意韵悠长 = (make a) deep impression 激情 = passionate/intense 内敛 = reserved I concocted: That silky-smooth and pale skin wrapped in a black dress. It made her stand out and carve a deep impression of being passionate yet reserved into everyone's mind.
Since I can't contribute to a better answer, here's a link: https://resources.allsetlearning.com/chinese/grammar/Main_Page Chinese is pretty neat to learn. Vocab + grammar and you're set for your future translations (let's ignore classical text). So, I should brush up on my grammar too. I'm not sure whether it should be 'passionate restraint' or 'restrained passion' at this point -_-;;.
Based on the context (yes, I googled it up because I was unsure too), it's describing a hot woman walking in a tight black dress. I gave up on deciding which of those two I should focus on and just made them separate.
意韵悠长与激情内敛: lingering charming and full of inner passion . that's my best try..hope it helped. 激情内敛 is describing she is in passion/energetic ,but not in an extroverted way.(maybe due to she is shy, or she don't want to act like she is seducing you)