THE LATIN ALPHABET VVAS AROVND AT THE TIME. VVHETHER IESVS KNEVV ABOVT IT IS A DIFFERENT MATTER, THOVGH HE DID HAVE SOME RVN-INS VVITH THE ROMAN EMPIRE, SO MAYBE?
He spoke Aramaic, but he was Jewish and Jewish people learn Hebrew reading and writing. He was well versed in scripture, so he probably did know how to read. The Bible talks about him spending a lot of time at the temple as a child, where he likely learned to read and write.