This is the 11649th most frequent Russian word.
жестче
"Жестче" means "tougher" or "harder."
Here, 'жестче' is used in a comparative sense to indicate a need for increased firmness or severity in actions.
Нужно действовать жестче, чтобы достичь результата.
We need to act tougher to achieve the result.
'жестче' is indicating a comparison over time, showing that discipline is intensifying in its strictness.
С каждым годом дисциплина в школе становилась жестче.
Each year, discipline at the school became stricter.
In this case, 'жестче' is used to compare the firmness of physical objects.