This is the 475th most frequent Italian word.
perdere
"Perdere" means "to lose."
Here, 'perdere' means 'to lose,' referring to an abstract concept such as hope or faith.
Non perdere la speranza, andrà tutto bene.
Don't lose hope, everything will be fine.
In this context, 'perdere' is used to indicate the physical loss of an item, the keys.
Ha perso le sue chiavi ieri sera.
He lost his keys last night.
In this sentence, 'perdere' means 'to miss' as in failing to catch an opportunity or event, like a train.