The correct sentence is: "Escribid en los cuadernos" And it means "Write in the (your) notebooks"
unos cuadernos
notebooks
Translation: Sacad vuestros cuadernos OR Saquen sus cuadernos
It means "take out the notebooks" when adressing a familiar group of people.
The plural form of cuaderno is los cuadernos.
Sí, hay cuadernos en la clase. (Yes, there are notebooks in the class.)
los cuadernos
Literally it means "some notebooks". In some places, though, it might also mean "some pals", but that's slang
Sacad los cuadernos (correct spelling) Take the notebooks out (you, familiar plural)
No, "cuadernos" is a plural noun meaning notebooks in Spanish. It is not a definite article. Definite articles in Spanish are "el" (masculine singular), "la" (feminine singular), "los" (masculine plural), and "las" (feminine plural).
"Una vela" is a candle.