This is a variant of {{Citation needed}}, used inline in the article where a claim requires an additional source. This most often arises when:
The citation provided is to a weak source (primary, tertiary, vague, low-quality) but the claim is not dubious enough to delete outright, and the imperfect source should be retained, e.g., because it was the first to report on the matter and this is significant.
The claim is one ("several studies demonstrated ...", "various newspapers reported ...", etc.) that requires multiple sources (or a single source, which has not yet been provided, that summarizes multiple prior sources and makes the same multi-source claim Wikipedia is repeating).
The claim is multi-part and the current citation only sources part of it, e.g., "1929–2006[1]" where the source is a 2005 book that provides the birth date and we have no source yet for the death date.
If the citation simply needs to be replaced, use {{Better source}}.
If there's no source for the claim at all, use {{Citation needed}}.
If multiple additional sources are needed for a block of material with multiple claims, do not use this inline template to tag the entire block; either use it to flag specific unsourced statements, or use a block template like {{More citations needed section}} or the article-wide {{More citations needed}}.
This template can be used inline where a claim requires one or more additional sources. For example when the claim is one that requires multiple sources ("several studies demonstrated ...", "various newspapers reported ...", etc.)