This is the 447th most frequent Italian word.
facile
Easy.
The word 'facile' here is used as an adjective to describe how uncomplicated solving the problem is.
Questo problema è facile da risolvere.
This problem is easy to solve.
In this sentence, 'facile' is used to express the degree of challenge in the action of making friends.
Fare amicizia con lei non è stato facile.
Making friends with her was not easy.
Here, 'facile' operates as an adjective to compare solutions based on their simplicity or ease.