This is the 2894th most frequent Spanish word.
simples
Plain or simple.
In this sentence, 'simples' describes 'problems', emphasizing their easiness or lack of complexity.
Los problemas eran simples, pero los ignoraron.
The problems were simple, but they were ignored.
'Simples' indicates that the exercises are straightforward or easy to understand.
Estos ejercicios son muy simples para comenzar.
These exercises are very simple to start with.
Here, 'simples' modifies 'cosas', indicating 'things that are simple or uncomplicated'.