I don´t know in wich palette is located the block that is coneccted to the error wire and what is this for, hope you can help me
There are two things connected to the error wire.The first seems to be some custom subVI.
The second is the optional conditional terminal and is part of the FOR loop. Right-click the FOR loop and check "conditional terminal" to show it. It will alow early termination of FOR loops, even before all iterations have completed. You can switch it to (A) Stop if true (or error) or (B) Continue if true (or no error). Your code shows option B.