Simplify the following text for a Grade 3 native English-speaking person.
Original: Leif Ericson ( or in English ; ; c. 970 â `` c. 1020 ) was a Norse explorer who is regarded as the first European to land in North America ( excluding Greenland ) , nearly 500 years before Christopher Columbus .
Simplified: Leif Ericson ( c. 970 â `` c. 1020 ) was a Norse explorer .