i was reading through a instructional and i came upon this term.

Hourglass stance -

This is a dangerous but necessary position in hitting. It happens at the tail end of your cross. Be ready to duck and cover. Your cross will put you in a bob position. You should be ready to stay low and elbow block, weave under, or jab to correct your posture. DO NOT just stand there fully extended with nowhere to go.

so i was just wondering what an elbow block in boxing is, and if i could get an example. via youtube.