This is the 6139th most frequent Spanish word.
amancio
"Amancio" is a Spanish masculine given name; it does not have a specific definition beyond being a proper name.
In this sentence, 'Amancio' is used as a proper noun indicating the name of the person who arrived early.
Amancio llegó temprano a la oficina.
Amancio arrived early at the office.
Here, 'amancio' is used colloquially to refer to a financial benefit or dividend, which may occur in certain Spanish-speaking regions.
El amancio de esta semana fue particularmente grande.
The dividend of this week was particularly large.
Again, 'Amancio' is used as a proper noun, referring to a person's name, and is elaborated with a descriptive clause about his dedication.