From the article:

The Cow is a meme opening system popularized by content creator WFM Anna Cramling. Players can go for the Cow setup as both White and Black, and the game usually leads to a solid but possibly cramped position.

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The Cow is an opening system characterized by a piece setup that rarely changes regardless of the moves played by the opponent. The Cow setup involves putting the central pawns on d3 and e3 and the knights on b3 and g3. Black can also play The Cow setup with pawns on d6 and e6 and knights on b6 and g6.

The Cow setup aims to develop the minor pieces and later attack the opponent's center. While The Cow is objectively not a sound opening, it still results in a playable position, at least according to chess engines.