This article has a nice infographic:
https://multimedia.scmp.com/infographics/news/hong-kong/arti...Basically Hong Kong right now, has a whole bunch of extradition treaties with 20 countries[1], just not with both China governments, due to the existing law. The bill fixes this.
Also, the 19 year old HK man admitted to the crime [2], however due to the the crime being committed outside HK, he can't be tried for manslaughter in HK; the HK authorities can only charge him with "money laundering" of his girlfriend's money and property (again [2]). He is currently serving the sentence for money laundering, and he's going to be released in October. However if this bill is passed he can be extradited and tried for murder in Taiwan.
[1] With Australia, Britain, Canada, the Czech Republic, France, Finland, Germany, India, Indonesia, Ireland, Malaysia, the Netherlands, New Zealand, the Philippines, Portugal, South Korea, Singapore, South Africa, Sri Lanka and the United States
[2] https://www.scmp.com/news/hong-kong/law-and-crime/article/30...