This is the 12457th most frequent Spanish word.
matarla
"Matarla" means "to kill her" in English.
Here, 'matarla' is used literally to mean 'to kill her,' referring to physical harm.
Voy a matarla si continúa portándose mal.
I will kill her if she continues behaving badly.
In this context, 'matarla' is used figuratively to express frustration or severe dislike towards the movie, which here carries a feminine identifier.
La película fue tan aburrida que casi quise matarla.
The movie was so boring that I almost wanted to kill it.
Here, 'matarla' is directly referring to the act of eliminating a fly, where 'la' represents the feminine gender of the noun 'mosca.'