To help expand your English comprehension: English idioms.

Tip

of the iceberg

What it means: the small noticeable issue that is part of a much larger issue.

"This is only the tip of the iceberg, we have many more miles to go."

"The shouting matches you've witnessed between John and Joe are just the tip of the iceberg, as they have been fighting like this since childhood."

(Please feel free to ask for assistance.)