This is the 138th most frequent Spanish word.
espera
"Espera" in English means "wait" or "waiting."
Here, 'espera' is a command (imperative form) directed to 'you' (informal singular), meaning 'wait'.
¡Espera! Olvidaste tus llaves.
Wait! You forgot your keys.
Here, 'espera' is used as a noun meaning 'wait' or 'waiting period'.
La espera en el hospital fue más larga de lo esperado.
The wait at the hospital was longer than expected.
In this sentence, 'espera' functions as a verb in the present indicative form of 'esperar', meaning 'to wait' or 'to hope'.