Translation:Pencils are things.
So I actually had some trouble with this 이/가, 은/는 business, but I think I figured it out no thanks to the phone app. I figured that 이/가 is used when the thing you're talking about it the subject, e.g. THE house, THE apple and THE milk. Whereas 은/는 is used when you have a general statement. An apple is a fruit, milk is a liquid. A (Some/any) house is a building.
You can see 'tips and notes' before you click on the lesson. This will give more examples and details about what you're practicing. In this case, you'll see a detailed explanation about the particles, articles, subject markers and the like. It's the lightbulb icon above the 'start' button.
I had this same question, duolingo isn’t really meant for explaining more for knowing the word and memorising it. Anyway 은/은 almost always appear after the first noun in ‘Basics 1’ Koreans put this particle at the end of the first noun like this for an example: 저는 (name) 입니다. And also there r 2 other sentence structures for this particle. 1 more thing 은 is after a consonant 는is after a vowel. If u want to knkw more or ur still confussed. //www.youtube.com/watch?v=XOy8bBId3zU
Actually, sort of but not really. It's a particle that shows that the word it's at the end of is the subject of the sentence. It's not translatable but due to korean's sentence structure where the verb is at the end of the sentence, it's essential in determining what the sentence is about.