Harsha was trying to understand tenses. She was just starting to understand the different Present tenses – Simple Present, Present Continuous, Present Perfect and Present Perfect Continuous tenses. She met Jay, with whom she had this conversation. And lo and behold! Tenses suddenly started making sense.
Harsha: Hi! My name is Harsha. Who are you?
Jay: Hi Harsha! I am Jaykant. But people usually call me Jay.
Notice how Harsha and Jay are introducing themselves. They tell each other their names. Names are facts – things that we can definitely find out if they are true or not i.e. either they are true or false. There is no other way of looking at it. Notice how when stating facts such as their names, they use the simple present tense. Also, Jay mentions that people usually know him as Jay and not Jaykant. These kinds of habitual (repeated) actions are also conveyed through the simple present tense. ‘Is’, ‘are’, ‘am’, ‘call’ are all verbs in the simple present tense.
Harsha: It is nice to meet you, Jay. What do you do?
Jay: Right now I am working on a project for the government. I have completed a Bachelors in Chemistry just this April.
Notice how Jay is talking about what he is doing continuously or regularly these days. Such actions are used in the present continuous tense. The next sentence states his action which he completed just recently, and is valid even now at present. Such actions use the present perfect tense.
Harsha: That is wonderful! Don’t you want to get a Master’s degree?
Jay: Yes, I do. I have been studying every night for the entrance exams.
It looks like Jay started the process of studying at some point in the past and it continues even now. Here the process and result are both important. So he uses the present perfect continuous tense.