This is the 10695th most frequent Spanish word.
defensiva
"Defensiva" means "defensive" or "defense" depending on context.
Here, "a la defensiva" means "on the defensive," describing her behavior as guarded or protective when discussing personal matters.
Ella siempre está a la defensiva cuando hablamos de su pasado.
She is always on the defensive when we talk about her past.
In this context, "defensiva" refers to the nature of the strategy as being focused on defense in a sports match.
El equipo adoptó una estrategia defensiva para proteger su ventaja.
The team adopted a defensive strategy to protect their lead.
Here, "defensiva" is used as an adjective describing the barrier, indicating its purpose to provide defense.