What does “tip of the iceberg” mean?

The phrase “tip of the iceberg” is used to refer to a situation in which you or someone else is seeing only a small part of what is really a bigger problem. So, the iceberg is used to refer to the fact that there is a very big problem, and the “tip” is a small part of that iceberg, or a small part of the bigger problem. The phrase has a negative meaning to it – and is usually used to describe situations or people that are difficult.

Here’s an example of it’s usage:

“Tip of the Iceberg” In a Sentence

"When our CEO laid off a few people a couple of months 
that was really just the tip of the iceberg since now over
200 people have been laid off."