I wish Duo could turn this into a whole sentence. It's harder to memorize.
Anyway, "kaca" means "glass", "mirror", "page (of a book)" or "example". And "mata" is "eye". What a straightforward combination of expressions!
Why plural?
"Glasses" is always plural in English. there are a few such words, like trousers, scissors...
Ga bisa lihat apa pun tanpa kacamataku!