Going concern is a term used to denote a company that has sufficient means to function for the foreseeable future.
While the term itself is a positive one, the term going concern is usually only encountered when there is a problem with a company. If a publicly traded company has discovered that there is a significant risk to ability to survive (e.g. lack of funds, impending government regulation, pending litigation etc.) it is required to disclose the risk it may go bankrupt to investors in its SEC filings. This is known as a going concern warning. Obviously a going concern warning is a huge red flag for would be investors.