Dimethyl ketones are a class of organic compounds that share the common structural element of a methyl group attached to a carbon atom in the keto group. A keto group is a group formed by an oxygen atom and a hydrogen atom. Acetone is one of the most famous representatives of dimethyl ketones.
Dimethyl ketones are typically colorless substances with a pungent odor reminiscent of the smell and taste of acetone. Most dimethyl ketones produced in the laboratory are non-flammable, and some are solvents.
This is a "standard" phrase that is used in most biochemistry textbooks - a title to describe some reaction or structure (term). In Wikipedia terms, it is a piece of text used to link to biochemical texts for an encyclopedia, usually Wikipedia. If you need articles in which only the title is written or in which only the definition is given, such articles are needed as an addition to your articles as a way to add a popular science style (as everyone can do, so can I, but the process may take several years), and not as a missing part.