You can’t! You just know how it is said, you just know what is its name, just like when you look at a picture of an apple and you know it is an apple, and you say it is an apple.
It is the same as the word “the” you just know what it is called. Over the years, and it seems to be dependent on the decade, there is argument about what is best way to teach a child to read.
Is it whole word or phonics? Or probably a combination of both? Many words in English sound differently to how they appear. Many words in English are spelled differently to how they appear.
They are recognized and experienced readers know how they sound. Words like rough, said, laugh are words that can’t be decoded using sounding out strategies. Some words just have to be recognized.
This article suggests this is an early evolutionary ability we developed. Reading is a man made activity not found in nature but visual recognition of shapes is an early ability we had. Perhaps phonics was introduced later by man and is a method of reading that has to be taught, whereas whole word recognition is something we just know how to do, some better than others.
In our practice we try to establish why some children have difficulty in learning to read. Is it due to visual factors or is it due to auditory phonological factors or a combination of both.