Wa Alaikum Assalam Wa Rahmatullahi Wa Barakatuhu,
Regarding Arabic Vocabulary & root words, it develops over time. Take the first step which is to learn grammar and Inshallah everything else will become easy with time.
Which book(s) are you using to learn Arabic? Have you learned Arabic Grammar? If you are fluent in English then I recommend using Medina Books to start learning Arabic, use link below to download free Medina books and several other resources available to learn Arabic Grammar.
http://www.lqtoronto.com/downloads.html
If you are fluent in Urdu language then I suggest you to download books from the following website:
https://tanzeem.org/book_categories/asaan-arabi-grammar/
You can also use some apps to understand in depth analysis of any word in Quran, one app I would recommend is:
https://apps.apple.com/gb/app/quran-word-by-word/id588198510
It gives all form of a verb along with the root letter. Or you can also use, the following app ( which is great for tafsir but not so much when it comes to in depth word analysis):
https://www.gtaf.org/apps/quran
Overall, this process takes time and requires patience and dedication. That's why it is always best to learn this with some friends in a group to make sure we stay on track. May Allah make it easy for you to learn the language of Quran. Ameen!
Ma'aSalaam