This is from the Standard Course Book of HSK5, chapter 20.
About the literal translation of this 就是一进街口靠墙的一个小棚子:
就是(was)一(a)进(classifier)街口(street entrance)靠(leaning against)墙(wall)的一(a)个小(small)棚子(shed)
I think I need much help to make it make sense. Why twice 一? 进 is a classifier (for the 街口) or it means in / into? I think I have perplexed all the sentence structure of [subject object verb adjective noun etc.].