Scotland

While there are no signs of William Wallace in this poem, it's still all about Scotland. A highland lass? Check. References to the geography of Scotland? Check. Inspired by Wordsworth's tour of Scotland in 1803? Check. So… why Scotland? Well, if you lived in England in the early 1800s, Scotland was the "other"—a place far up north where everybody was just a wee bit different than those down south. In "The Solitary Reaper," the Highland lass symbolizes the exoticism and difference of the world "up there." She sings in a language the speaker cannot understand, and yet he's totally down with that because, well, it's amazing.

• Line 2: The speaker tells us that he has just encountered a "highland lass." The speaker uses a Scottish word to make it clear that this is not a woman, but a "lass"—a totally different (Scottish) type of being. 
• Lines 15-16: None of the cuckoo-bird's songs, breaking up the silence of the seas in the Hebrides, can compare to the woman's song. The Hebrides, a group of islands off the northwest coast of Scotland, symbolize the very far away, what we would call "the ends of the earth." Even though the woman is Scottish, she is unlike other Scottish things (the cuckoo birds in the Hebrides, for example). 
• Line 17: The speaker wants to know what the woman is singing because she's from Scotland, and is singing in Scots Gaelic (a.k.a. Erse). The speaker's inability to understand the woman underscores how different the two are culturally and linguistically.