"My older son"
Translation:Мій старший син
I'm not sure how they do transliteration in this course, but if I had to guess it would И=Y and I=І
So it should've been "Miy starshyy syn".
And I would really recommend abandoning Latin script, with your level 10 you should be more than ready for Cyrillic unless there is some technical issue that prevents you to do so