Phonics is the technique of "sounding out" words you don't recognise, which means you can learn to read without having someone to help you with every word. Phonics is based around the individual sounds that we make when we speak; these are called 'phonemes'.
For example, the word "cat" has three phonemes - C - A - T. When you have learned to sound out words, you'll be able to match the sounded word with a word you have heard before.
You will become faster and faster with decoding, and your vocabulary will grow rapidly as you learn new words.
In this course, the main goal is to be able to see a word and "sound out" the letters in the word - it will sound like a word you already know. Phonics gives you the ability to read English.