It depends on the nation. The UN collects data. Afghanistan is 62.7% illiterate, for example. Further, Almost all refugees to Denmark have zero Danish language reading and writing skills. They must learn all of these. Slightly more (but shockingly few) have any English reading and writing skills.
Surely it isn't surprising to you that refugees have limited European language skills?
That definition of a refugee is perfectly compatible with the definition of a an immigrant. As per the definition, all refugees are immigrants. Not all immigrants are refugees.