Final answer:
The '+' symbol at the bottom of a text box usually stands for the option to increase font size in text editing software.
Step-by-step explanation:
The "+" (plus size) symbol at the bottom of a text box often indicates an option to increase font size. When you see this symbol in a word processor or another text editing software, clicking on it typically makes the font size larger. It’s a visual cue for users to understand they can make the text more prominent if needed.