Translation:I passed by the intersection.
This is so confusing without Kanji. I would have laughed at this statement about a month ago, however, now that i have been learning kanji, the sentences with Kanji that I know, are able to be translated quickly in my mind. I might not know all the sounds of the Kanji but I know their meaning. Knowing the meaning is the most important thing. Blind translation from Japanese to English really dont help you learn.
When you learn a kanji you learn its pronunciations. When you learn a word that contains kanji, you learn which of those pronunciations that specific word uses. With the concept of furigana, there is literally no valid argument for Duolingo to not use Kanji wherever possible.
It's when you have the pronounciation of the kanji written alongside with it in hiragana, you see it a lot in manga and books for an younger audience. Cause you know, it takes all your school years in Japan to learn the necessary kanji even for words you already use on a regular basis.
Firstly, you can search for "remembering the kanji" at google for a well known book/pdf which includes most kanji and gives the meaning and the stroke order of each, starting from easy ones and going higher up in complexity. You may not be able to learn how to say them but you will learn ways to remember them and write and recognize them.
For the pronounciation of kanji I use youtube for some basic lessons and the "kanjialive" site for an online dictionary with stroke order/meaning/pronounciation/words including each kanji and hints.
I think there are two main causes of confusion here. The first is that そば is a noun here, even though it is often best translated by English words that aren't nouns, such as by, nearby, or next to. When anything is modified by something plus の, it is handy tip off that it is a noun. So the word そば actually means 'a place by / near / next to' something. Some dictionaries give the English nouns 'vicinity' & 'proximity.'
Second, the verb とおる is not simply 'go,' but rather 'go on / along' (a road, etc.) or 'go / pass through' (a space [通る] or object [透る] ). It is transitive, so it takes a direct object marked by を. So even though we wouldn't say it this way in English, the sentence literally means: (I) go / pass through an area next to the intersection.
BTW you would use そば with に rather than を to indicate the location of something, for example: わたしのそばにあります / います (Something / someone is next to me).
This leads into the old Japanese pun, playing on another meaning of そば, which is buckwheat noodles.
そばはすきですか Do you like soba (noodles)?
わたしのそばは? How about my 'soba' (=being next to me / by my side)?
My guess is that it should technically be. But, as has been mentioned many times before, Japanese is very contextual. The context of one passing my some random intersection by using the word "an" is a bit fringe given that we're learning directions and not just some random words. Saying that one is passing a particular intersection the word "the" would be more appropriate.