Sorry for a stupid / easy question, but I need to figure it out. I am going to a course on datacamp, I can’t taste that description: 
I do not understand the last sentence - what exactly do characters (\) do?
It would be more correct to say that the "\ s" with one slash is a space character, and two slashes are written so that the development environment (ide) is understood and skalala. It is called the escape character. Although in different languages ​​the shielding symbol seems different. There is also a backslash if I remember correctly "/ \ s"
A metacharacter is made from the letter "s", meaning space. Called "shielding."
If you simply write "s" in a regular expression, then the letter "s" will be searched. If you write " \\s ", then spaces will be searched.
Source: https://ru.stackoverflow.com/questions/943990/
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\s. In the general case,"\\"=\, i.e. The same literal backslash character that is used to set / form "shorthand character classes" (character classes) and escape special metacharacters for regulars. - Wiktor StribiĹĽew pm