Short answer. You step into the co-owner's role for administration and fruits. Article 582 of the Civil Code gives the usufructuary of a share in a thing held in common all the rights the owner would have over administering the property and collecting its fruits or interest, for as long as the co-ownership lasts.
What the law says
The usufructuary of a part of a thing held in common shall exercise all the rights pertaining to the owner thereof with respect to the administration and the collection of fruits or interest.
Civil Code, Article 582 — Usufruct of an Undivided Share. Read the full provision →
You exercise the co-owner's rights, not lesser ones
Article 582 says the usufructuary of a co-owned share shall exercise all the rights pertaining to the owner thereof with respect to the administration and the collection of fruits or interest. The key phrase is "all the rights" — on the two matters the article names, administration and collecting fruits or interest, you stand exactly where the co-owner who granted you the usufruct would stand. You are not given a diminished version of their role; within that scope, you exercise it fully. The co-owner who granted the usufruct does not lose ownership of the underlying share in the meantime. Article 581 lets an owner whose property is subject to another's usufruct still alienate it, though not in a way that alters its form or substance, or that is otherwise prejudicial to the usufructuary. So the co-owner can sell their undivided share, but the buyer takes it still burdened by your usufruct.
What happens if the co-ownership ends
Article 582 also answers what happens if the co-ownership is eventually dissolved: should the co-ownership cease by reason of the division of the thing held in common, the usufruct of the part allotted to the co-owner shall belong to the usufructuary. So if the property is later partitioned among the co-owners, your usufruct does not simply evaporate — it follows the specific portion that ends up allotted to the co-owner whose share you held the usufruct over.
What the article limits itself to
Article 582 is specific about which rights transfer to you: administration and the collection of fruits or interest. It does not say you inherit every right a co-owner has in every respect — for instance, whether you can act in the co-owner's place on decisions about the property that go beyond administration and fruit collection is not something this article addresses. Where a question falls outside those two named areas, this article alone does not settle it.
What this means while the co-ownership continues
In practical terms, you can manage the property and collect what it produces to the same extent the co-owner could, for as long as the co-ownership lasts. If partition happens later, your position converts automatically to a usufruct over the specific piece the co-owner ends up with, so the usufruct is not tied to the undivided share forever — it is designed to survive the transition from co-ownership to separate ownership.