If the question being asked is "Nos recomiendas esta peluqueria?", why is the answer "Si, les recomiendo."
Why is that? I don't understand
If you and a group of friends (nosotros) are asking about the peluqueria, then the answer goes to every one of you (ustedes) so it would be les (les recomiendo a ustedes) instead of le (el, ella o usted).
In other countries, the usual answer would be:
Sí, se la recomiendo / Sí, os la recomiendo / Sí, la recomiendo / Sí, claro. Or simply, Sí.
To me, Spanish speaker, Sí, les recomiendo sounds awkward too. The indirect object les (a vosotros/a ustedes) is clearly understood because you have a dialogue. There isn´t a real reason to emphasize ´to you = les´ but the direct object la (peluquería) because it is the topic in this conversation.
A different case would be if the speaker introduces the topic with a ¨Si quieren cortarse el cabello, les recomiendo esa peluquería.¨
But I´m not saying that the posted example is ungrammatical. I think it´s a question of discourse in action.
Welcome to the forum!
You use "les" in that case because it is the indirect object. The direct object is understood - I recommend it (understood) to you-all.
Les is the indirect object pronoun for ustedes.