You can tell them your name but depends on people to people, when you are going to get admission in some institution you will have to tell everything even other details. For online reservations or booking of tickets you will have to furnish other details. But meeting some unknown person whom you don't know and will even not meet them in future may cause some problems, don't disclose your personal details, mobile no, bank account no, they may meet you in airport, railway stations, theaters, hospitals. Keep safe distance with unknown people.
If you are asking whether or not it's safe to tell someone online your name, first names are fine, but full names are not safe. Also refrain from posting personal contact information like where you live, what school you go to, your phone number, email address or usernames on other sites. Basically, do not give someone online any information so they can contact you offline.