General synonyms:
* Educated
* Learned
* Knowledgeable
* Erudite
* Well-read
* Informed
* Cultivated
* Enlightened
Synonyms specifically related to reading and writing:
* Fluent
* Proficient
* Skilled
* Able
* Competent
* Capable
* Articulate
* Eloquent
Synonyms related to a specific subject:
* Computer literate
* Financially literate
* Media literate
The best synonym will depend on the specific meaning you want to convey.