"what is called" refers to "communicative approach to language learning". The phrase 'what is called' is optional in your sentence but helps the reader understand that "communicative approach to language learning" is the name of this particular language teaching approach.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Microctg... are oriented towards what is called the communicative approach to language teaching.~ are oriented towards the thing that has the name 'the communicative approach to language teaching'.