読み書きができない

cannot read or write

→ 読み書き
phrase Rare #36,505
cannot read or write Literally means “cannot do reading and writing.” It describes being unable to read and write, often referring to a child’s current ability or someone’s literacy. The related positive form is 読み書きができる, meaning “can read and write.”
JA: 弟はまだ読み書きができない。
EN: My younger brother still can't read or write.

息子はまだ読み書きができないんだ

My son still can't read or write.

彼女は読み書きができないんです

She can't read or write.

お前は読み書きができない

You can't read or write.

— 紅夢 (1991)

彼らは普通に読み書き全くできないという意味読み書きができないのではない

It doesn’t mean that they are completely unable to read or write in the ordinary sense.