Whitespaces matches anything that is considered a whitespace character. It is equivalent to '[[:space:]]'.
For example, in the gopr.txt file, we match all the lines that contain 'e' followed by whitespace and 'd' using the '\s' operator. It will print all the lines in which there is a space or tab between 'e' and 'd', as follows:
$ awk '/e\sd/' gopr.txt
The output on execution of the preceding code is as follows:
e de d