You use what in expressions such as what is called and what amounts to when you are giving a description of something.
Meanwhile, most young people in the West are expected to leave what could be life's most momentous decision - marriage - almost entirely up to luck.
Do I correctly understand that it means - what could be life's most momentous decision is up to luck
Thank you.up to someone phrase
1. if something is up to you, you are the person who makes a decision about it