Hola Emanuel,
In sentence 1:
Espero que lo hayáis pasado fenomenal en Chile.
I hope that you had a great time in Chile.
we are using the expression "pasarlo bien" which means "to have a good time"; it is idiomatic as you can see, but if we translate it literally it'd be "to spend it well". That "it" would be the "lo".
Other example:
Lo pasé genial en su fiesta de cumpleaños.
I had a good time at his birthday party.
Also note that this "lo·" is "la" in some Latin American countries, e.g.
¿La pasaste bien?
In sentence 2:
Esperamos que lo hayas terminado a tiempo.
We hope that you have finished it on time.
here "lo" is a direct object pronoun refering to something masculine singular. They could be talking about a project or an exam...
Esperamos que hayas terminado a tiempo tu proyecto/tu examen. -->>Esperamos que lo hayas terminado a tiempo.
I hope this clarified it for you.
Un saludo
Inma
