Phonological Awareness
The way that sounds are stored in our brain and the ability to manipulate those sounds. Under this is also Phonemic Awareness which is when those sounds get connected to the letters of the alphabet. A big part in learning to read is having a good handle on these sound structures.
How to and reseach behind Phonological and Phonemic Awareness
https://www.readingrockets.org/article/how-now-brown-cow-phoneme-awareness-activities
https://www.readingrockets.org/helping/target/phonologicalphonemic
A PBS series showing the ins and outs of teaching reading and writing
https://www.readingrockets.org/launching