In Google Sheets, I want to populate cells in Column A with certain conditions, based on the contents of column B

Question

In this sheet, https://docs.google.com/spreadsheets/d/1MR0n1FoutASbuwiNJS7FrcQhxHF6Bo03oVs9RZPo9g4/edit?usp=sharing

I am trying to have column B be populated with cel