Don’t get confused with the concepts of Angular and RxJS
We have pipes concept in Angular and pipe() function in RxJS.
1) Pipes in Angular: A pipe takes in data as input and transforms it to the desired output
https://angular.io/guide/pipes
2) pipe() function in RxJS: You can use pipes to link operators together. Pipes let you combine multiple functions into a single function.
The pipe() function takes as its arguments the functions you want to combine, and returns a new function that, when executed, runs the composed functions in sequence.
https://angular.io/guide/rx-library (search for pipes in this URL, you can find the same)
So according to your question, you are referring pipe() function in RxJS