It'll still work. It won't get updates. In particular it won't get updates to the hundreds of hacking vulnerabilities that probably exist undiscovered (or at least unreported). In other words Microsoft will stop fixing all the broken stuff. Microsoft will also stop answering questions about it, but as a consumer they wouldn't have answered your question anyway.
Eventually software manufacturers will stop making software to run on it, or won't allow updates any more. For example Python stopped running on Windows 7 in 2020 when Microsoft stopped paid for support of it.