Broad and Board are easily confused words, just change a few letters and you have a whole new word. The spell-check of most word processing software programs would not catch a slip-up among these three words. As long as it’s a word and it is spelled correctly, spell-check keeps on scanning the document.
Broad is an adjective, it describes something having wide dimensions or girth, or a diverse selection.
Broad can also be a noun. In mid-20th century slang, it’s also used to refer to a woman.
Board is a noun. It means a slice of wood or other hard material used to construct something. It can also be short for “surfboard.”
The following sentence uses both words correctly:
To make the most of every conversation and keep anyone from getting bored, be able to talk about a broad range of topics.
See a related post, Board vs. Bored.