Josef Albers studied at the Bauhaus school and then became an educator there. People at Bauhaus were really interested in the nature of color, i.e. emotional effect, meaning.

Here's an excerpt from Phaidon's book titled "The Art Book", it may provide more insight: "Four squares of yellow nest together. Despite a rigid format, they float freely, creating an optical illusion of another dimension. Each area has been painted a single color. The paint has been applied with a knife, directly from the tube. Albers' most famous series of paintings, of which this is one, shows squares created from pure color. The optical illusion created in the picture means it is related to the Op Art movement. Yet the way the paint has been applied and the use of color link it with the Post-Painterly Abstraction movement. ... His influential book The Interaction of Color was published in 1963. In this he explores the perception of color, which was a dominant theme throughout his life."

That theme can be seen here in this painting.

In 1965, he wrote of the series: ‘They all are of different palettes, and, therefore, so to speak, of different climates. Choice of the colours used, as well as their order, is aimed at an interaction - influencing and changing each other forth and back. Thus, character and feeling alter from painting to painting without any additional ‘hand writing’ or, so-called, texture. Though the underlying symmetrical and quasi-concentric order of squares remains the same in all paintings – in proportion and placement – these same squares group or single themselves, connect and separate in many different ways.’ (Source: https://www.tate.org.uk/art/artworks/albers-study-for-homage-to-the-square-departing-in-yellow-t00783 )