on the tip of one's tongue

on the tip of one's tongue (idiom): to be at the point of remembering something. When a person cannot remember something. I cannot remember what day I have to go to the office...

- Oh, what is her name again? It's on the tip of my tongue, but I just can't remember it.

Spanish: 'en la punta de la  lengua' . Lo tengo en la punta de la lengua.