To speak nonsense or about something one knows little about.
Parler des bêtises ou de quelque chose qu'on connaît peu. (parler des betises ou de quelque chose qu'on connait peu)
"He was talking through his hat about quantum physics."
"Il était en train de parler sans savoir de la physique quantique." (il etait en train de parler sans savoir de la physique quantique)
to make significant progress or improvements
to say sorry to someone for something you did
able to understand things quickly
to wait for a short time
to dismiss something as unimportant
a family member who is considered a disgrace