It depends on which word processing program you use. It is green in several though this is not universal.
In Microsoft Word, a green wavy line indicates a potential grammatical error, such as a sentence fragment or a punctuation issue. It is a signal for you to review and possibly correct the highlighted text to improve the overall clarity and correctness of your writing.
Green wavy underline indicates grammar "mistakes" (you have to turn the grammar correction function on to have Word indicate it has found mistakes)
The word is mispelledA RED squiggly line means the word is misspelled. A GREEN squiggly line means that there is one or more extra space or tab characters that aren't grammatically needed.
The green line means a grammar mistake. The red line means a spelling mistake.
A line with half circles on a weather map typically indicates a warm front. This is a boundary where warm air is advancing and replacing cooler air. It is associated with the potential for rain or showers.
The red wavy line indicates Microsoft Word thinks the word you've typed is misspelled, or that you've inserted a proper name or jargon not in the Word dictionary. If you see a green wavy line, the application thinks you've used bad grammar. You can turn these features on and off under the Tools menu: Spelling and Grammar, Options. Notice the first item under Spelling says, "Check spelling as you type." When this box is ticked, the application checks spelling in real time and notifies you of (suspected) errors by placing a red, wiggly line under the word. If you find this annoying, you can turn it off by un-ticking the selection box. This is also true of the green squiggly line generated by the grammar checker.
It means it (most likely/probably) is a grammar mistake. However, I do think that Microsoft Word (any version) has and can make mistakes with grammar and/or spelling.
A red line with semicircles on a weather map typically indicates a warm front. This signifies an area where warm air is advancing and replacing cooler air, often leading to the potential for cloudiness and precipitation.
The green wavy line in Microsoft Word is used when Word think you make a grammatical mistake. (The red one is used when you make a spelling mistake) There should be an option in the Word, "Check grammar as you type". You can turn it off/on. Adding some Microsoft links with more information.
A red wavy line indicates a possible misspelled word.The green wavy line indicates grammar errors or sentence format errors.
The division sign is simple. Draw a short line similar to a dash like this - Put a dot on top of the line and put a dot under the line. That symbol indicates division.