Hi Luisfe!
How exciting it is to know that you're planning a trip to Dublin! There is a lot to see, both in the countryside and in the city. The easiest way to move around if you're leaving the city is by renting a car. However, you can also use
public transport to get to most places.
You are right about the mountains close to Dublin. The Wicklow Mountains are beautiful and a great day trip from the city. This is just one of several
day trips you can do from here.
Please also bear in mind that the travel situation during the next year is unknown. I would recommend you to check the
government site and the
Traveller's health article often. Here you will find more information about the restrictions (if any) taking place in Ireland.
Let me know if you need some more advice. I can also help in Spanish if it is better for you.
David