Is los a pronoun

Assuming that you are asking about "los" in Spanish, the answer depends on context.

The most common use of "los" is to mean "the" for a masculine, plural Word. For example, "the foxes" would be "los zorros". In this case, "los" is an article, not a pronoun.

A second use of "los" which is also common is to mean "them" for a masculine group. For example, "I see them" would be "yo los veo". In this case, "los" is a direct object pronoun, which is a type of pronoun.