Espía is guerrilla rank 4 in Libertad. It unlocks more weapons and gear for purchase and makes the Médico Supremo available from Juan.
Your guerrilla rank rises as you earn XP across Yara. Each new rank opens a new batch of weapons and gear for purchase, and some items say right in their unlock text which rank you need. The game shows either the feminine or masculine form of each title.
Médico is a healing Supremo, a good safety net for tough fights and co-op. If you go down a lot in base attacks, it is worth a look at this rank.
Fuego Loco
Lets out a ring of fire that burns nearby enemies and vehicles. Jumping in mid-air gives a short thrust forward.
Juice Injector
Boosts your speed and health and lets you perform Machete kills on any enemy, even in open combat.
Rank 2: Guerrillera
Libertad rank 2. Weapons and gear marked for Rank 2 can be bought from Juan and his Arms Dealers.
Rank 6: Sargento
Libertad rank 6. Weapons and gear marked for Rank 6 can be bought from Juan and his Arms Dealers.