Final answer:
A wavy red line under a word typically indicates a spelling or grammar error.
Step-by-step explanation:
When you see a wavy red line under a word in a document or text editor, it usually signifies a spelling mistake or a grammar issue. Most word processing software and text editors use this as a visual cue to highlight potential errors, prompting users to review and correct the identified word. The red line helps draw attention to the problematic word or phrase, allowing for easy identification and correction. It's a helpful feature that aids in proofreading and ensuring the accuracy of written content before finalizing it.
In essence, a wavy red line serves as a signal for errors that might need attention, guiding users to review and rectify potential mistakes within their written work.
Correct answer: indicates a spelling or grammar error.