El amigo
Las chicas 
Los maestros
El hombre 
El mujer
Los hombres 
La amiga
El estudiante 
Las maestras
Los mujeres
Feminine nouns usually begin with “La” if the word is singular, and “Las” if it’s plural. Masculine nouns usually begin with “El” if the word is singular, and “Los” if the word is plural. 
Una guitarra
Unos libros
Un deporte
Unos refrescos
Una bicicleta 
Unos teléfonos 
Una patineta
Unas bicicletas 
Un libro
Un television 
Both masculine and neutral nouns (nouns that aren’t really masculine or feminine) usually begin with “Un” if the word is singular, and “Unos” if the word is plural. Feminine nouns usually begin with “Una” if the word is singular, and “Unas” if the word is plural