My wife didn`t work in Canada during 2023, but she worked in Brazil. So, do we need to declare her money that she saved there?

If she is going to file a return in Canada, then yes. Where is goes depends on whether she is a resident or not. 

She is an international student, so she has a Student Permit Visa and I an Open Work Permit Visa.

Then she would enter her income from working in Brazil as part of her worldwide income. She won't be taxed on this income, but it's still needed to calculate certain income-based credits.