Timestamps operation

Hello, I have a problem with the use of timestamps.
I want to make the difference between 2 timestamps and convert them to H:min:s.

Welcome to the forum.

There are various ways to do that in node-red including using JSONata in a change node and JavaScript in a function node. Indeed, if the input timestamp data is in the correct format, you could do it with a simple subtraction.

You need to share with us the input data format.