"Son mis lápices, pero ella los necesita."
Translation:They are my pencils, but she needs them.
How would you know if it was 'they' vs 'these' in context? I was marked incorrect for saying These
In spanish you can drop the subject pronoun (ellos/they) because the verb is conjugated but not the demonstrative adjective (estos/esos), in this case you need to indicate which one you are using (these or those).
"Ella" is not drop because it is specifying it is she and not he (él) who needs the pencils.