On some illustrations, you have these text boxes which explain individual parts of the product. The text is not placed immediately beneath the item, because there's too little space to fit in. Instead, it provides a line (with or without arrow) pointing to the item in question and the text is more on the outside where the space is available.
Powerpoint has them under "legend" and they look like this:
In patent drawings these arrows typically have numbers only, but the purpose is also the explanation of some part of the product:
What's the name of this "textbox + line combination" so that everyone knows what I'm talking or writing about?
BTW: I don't even know the German (my native language) name of that thing, so I can't look it up in the dictionary.