Hi Avery Liu, "Otherwise" basically means different circumstance, or a different outcome. "You should get at least 8 hours sleep each night, otherwise you will feel tired" " I was advised to save my money for a rainy day, but I chose otherwise. Now I wish I had taken that advice". I hope this helps.

Otherwise here just means in other circumstances. For example: "Mike's car must have broken down, he wouldn't have been late to work otherwise." means Mike would not have been late to work if the circumstance[his car breaking down] was different.

Otherwise=if it were not for x. The trick is to find out what x is. A person who sells a car because they got a good price can say: "Did I get a good price? Yes, I wouldn't have sold it otherwise. " "Philip was a success in life because of the help he recieved from his many friends. He couldn't have been a success otherwise."

It means "in other circumstances," "if you were to make another decision." Hopefully you understand, because I cannot be more specific without knowing the context (and the missing if-clause).