Hi! I worked in the United States during the summer of 2018. On the "Foreign Income - Summary" page should I list my income in USD or CAD? Thanks!

Hi there! You should be inputting  your foreign income as USD. 

I guess it work with other currency ?

So in my case I just need to put my "other income" in  xxx euros and then put the proper exchange rate in the dedicated area ?

You will need to enter it in Canadian funds CAD- You will take the exchange rate from the bank of Canada

https://www.bankofcanada.ca/rates/exchange/annual-average-exchange-rates/