It evokes the image of someone speaking harshly and rapidly, like a whip lashing out.
Here are some examples of how it's used:
* "The teacher gave the student a tongue-lashing for talking in class."
* "After the accident, the boss gave the employee a tongue-lashing for not following safety procedures."
* "The coach gave the team a tongue-lashing for their poor performance."
Essentially, it means to be scolded very severely.