Figure out: to think about sb/sth until you understand them/it 弄懂;弄清楚;弄明白
We've never been able to figure her out.
我們一直沒能看透她。
I can't figure out how to do this.
我弄不懂怎樣做這件事。
get the hang of sth: to learn how to do or to use sth; to understand sth 掌握…的要領(lǐng);了解…的用法;找到了訣竅
It's not difficult once you get the hang of it.
你掌握了要領(lǐng)就不難了.