In this dialogue, two classmates greet each other casually by saying “Good morning.” At this stage, you are not expected to read Japanese yet—just listen to the sounds and focus on how the greeting is used.
There are two styles of spoken Japanese---polite and plain.
/ohayou/おはよう is a plain-style greeting used in a casual conversation between friends and peers. Both speakers here are using the same level of politeness.
Dialogue 2: Good morning between a student and a teacher