Questions & Answers about Esa lección es muy interesante.
Why do we use esa instead of esta or aquella?
In Spanish, esa indicates something that isn’t very close to you but also isn’t far away. If the lesson were right in front of you, you might say esta lección. If it were farther away, you might say aquella lección.
Why is lección treated as feminine?
Nouns in Spanish have grammatical gender, often unrelated to any natural gender. The word lección is feminine, so we need feminine determiners and adjectives (for example, esa, la, interesante agreeing with feminine).
Why do we use es instead of está?
Es indicates a permanent or general characteristic — in this case, describing that the lesson is inherently interesting. Está would be used for temporary states or locations, for example, La lección está en el libro (“The lesson is in the book”).
Why say muy interesante instead of mucho interesante?