In English you can call just about everyone by their first name.
In a professional setting you should generally choose to call people "Mr./Mrs..." or "Sir/Ma'am" the first time you meet them, but they'll probably ask you to call them by their first name. If someone introduces themself by their first name or asks you to call them by their first name, then calling them anything else could be considered rude.
In any other setting, you should always call someone by their first name.
If you're unsure, always call a person by the name they give you.
If someone called "John Smith" says "I'm John", always call him "John". If says "I'm Mr. Smith", call him "Mr. Smith". If he introduces himself as "John Smith" and you're in a professional setting, ask "What should I call you?".