You can use these personal pronouns when you're talking to others using Korean Language. You can see that some of the words were labelled with (humble) and (honorific). In Korean Language, they used different words when they are talking to people who are older or people who wasn't close to them to show respect.
Let see the use of 'I' for example; 나 (na) is used when we are talking to our friends or people who closed to us while 저 (jeo)-labelled (humble) is used when we're talking to older people or someone who is not close to us.