How vim cancels the key highlight after the search

These days, I've been learning python,

A few days ago, when I was doing my exercises, I was thinking of adding an IF clause to the Python method body.

However, if the following line, all need to do indentation, so, I in the Vim editor, lost the string substitution command

: 12,20s/^//

In this way, you can indent as many lines as possible, but the problem arises:

　　

Later, regardless of the creation of any file, as long as the use of vim editing, the beginning of the highlights appear; I'm so annoyed.

Today, in the afternoon, I found some information,

Just type on vim.

: Noh

It's all gone. Ha ha

How vim cancels the key highlight after the search