1. Third person singular preterite of 'aplicar-se' - to apply oneself, to dedicate oneself to something with effort and focus
She applied herself to her studies.
Ela aplicou-se aos seus estudos.
2. Third person singular preterite of 'aplicar' in passive/reflexive form - something was applied or put into practice
The new rule was applied to all departments.
A nova regra aplicou-se a todos os departamentos.