Algunos/as; unos/as are very similar, but algunos/as is often more specific than unos/as. ALGUNOS/ALGUNAS 1). In the singular, usually means some or any. ¿Has visto alguna mejora en sus estudios? - Have you seen some/any improvement in their studies? 2). Can be used as a pronoun. Algunos de mis amigos son médicos - Some of my friends are doctors. 3). In the plural, algunos/as usually means the same thing as unos/unas. Guardaré algunos/unos libros. - I ´ll keep some/a few books. UNOS/UNAS 1). Often the plural form of the indefinite article can be translated as "a few" or "approximately." 2). Other times unos/unas may not be translated at all. Ellos son unos chicos muy inteligentes - They're (some) very intelligent boys.