I always struggled in foreign language courses, even though people kept telling me I was good with languages.
Then my Dad took a Japanese course with me, and I realized what my problem was. Studying.
I have no clue how to study. Due to executive dysfunction, I find it extremely difficult to study for courses - remembering to do it at all, coming up with a plan for what to do, staying focused while doing it...
I'm smart and usually pick classes I'm interested in, so I can usually coast through without any deliberate studying. I read the text book once, research whatever caught my interest, and try my best to do my assignments (one big assignment at end of term is way easier for me than lots of little ones).
That doesn't cut it with languages. I'd have to be an incredibly gifted polyglot to even have a chance of passing a language class without studying at all.
My Dad, on the other hand, immediately figured out drills for us to do in Japanese, and kept reminding me to study Japanese with him. Plus, he and I would randomly get into conversations in Japanese (much to the annoyance of my Mom). I just barely passed Japanese, and it's directly because of him.