"a big jacket"
Rule: Adjectives in Arabic always come after the noun they are describing. Like in French, Italian, Spanish... etc.
If the adjective is attributive (describing the noun directly) then it follows the noun in all its aspects: Gender, definite article, number.
If the adjective is predicative (telling the status of the noun), the adjective would follow the noun only in number and gender.
I searched for this on Ecosia and eventually found this link: https://wals.info/feature/87A#2/17.9/144.7 So, apparently a 65% majority of languages, such as Arabic and Italian, are predominantly noun-adjective, whereas about 25% of languages, such as Finnish, English and Chinese, are predominantly adjective-noun. The remaining 10% are in a way or another impossible to categorize in either of those categories.
EDIT: Results of a brain freeze corrected.
The audio works for me here (on PC) but lot of people are complaining about it so I'm not sure what's the issue.
As for the font size, you can enlarge that (if you are using a browser on PC) using CTRL and (+). It will enlarge the page and text several times (I think up to 300%). In firefox here, when you zoom in, the percentage shows in the address bar on top - just click that and it will zoom back to normal. Probably most browsers work in the same manner, not sure. This is the easiest method probably; There are other settings in the browser but I prefer not to touch them.
If you are on a device, android or iOS, well unfortunately for me, I'm not into these. But I remember android has the option to enlarge the font as well gesturing to zoom in. Hope these work for you.
I think jiml and most others are referring to the app with these complaints. For some reason, a lot of the questions that involve actual sentences don't play samples in the app and only on PC. The app is the most convenient, though, so I hope they program this in soon :)
Bear in mind that this course has many mistakes and composed mainly of a mix of dialects beside the standard Arabic. The audio here is can be wrong in many times (months back, it was more than 50% of times wrong) - not sure if they fixed any of that. This is because the audio is recorded using a speech machine and a not a real human voice recording.
In Arabic, the adjectives always come after the noun. There are specific cases when an adjective comes before the noun but that's somewhat a different case and out of the scope.
Side note: جاكيت is an adaptation to the English word Jacket. However, there is an original word for this in Arabic even though not used in daily speech right now, and that's سُتْرَة (sutrah). Duolingo is teaching a mix of Dialect and standard.