What does your last name mean Quintero?

From Wikipedia:

Quintero is a Spanish surname originating in the Spanish region of Castile. The name comes from Quinto or Quinta which means "fifth". Quintero was a renter of Quintas (also known as Haciendas, Spanish for "Ranches"). The Quintero would rent one fifth of the land and would pay as rent one fifith of his produce of the land to the landlord.

From Family Education:

Quintero:

Last name origin & meaning:

Spanish: variant of Galician Quinteiro, a habitational name from Quintero in Ourense province, Galicia, so named from quinteiro 'farmstead'.

Based on both sources, I would say the name Quintero means "farmer".