The painting's title preserves some ambiguity as to what, precisely, is depicted within it. The 'characters' could be human characters or personalities, or they could simply be writing-like marks (in the way that letters are 'characters').
What do we see when we look at Characters in Yellow? The painting depicts a patchwork set of oblongs, all of them in different shades of yellow.
This design is punctuated by bold black lines. These lines could suggest a hieroglyphic style of writing known only to the artist himself, or them could (as is the case with Klee's paintings of more recognisable faces) be designed to represent facial features.
In all events, the appearance of Characters in Yellow is somewhat similar to another painting by Klee, 'Hafen', which was executed just one year after Characters in Yellow in 1938.
Hafen, similarly, deploys a background of coloured squares (this time, the oblong shapes are in blues, reds and other colours and not just yellows) with black line markings superimposed over the top.
Characters in Yellow was painted during the last few years of Paul Klee's life. Klee was a Swiss-German painter and he was known as a member of the German Expressionist movement, as well as an abstract artist thanks to abstract works such as Characters in Yellow. He was born in 1879 and died in 1940.
His earliest works were somewhat cubist in nature and in the period between 1914 and 1919 he also entered a 'mystical' phase of painting where he experimented with esoteric symbols. During this mystical period, he worked primarily with watercolours and began to gravitate towards a more abstract style of painting.
In the 1920s, he painted his now famous and distinctive pictures of faces ('Senecio' from 1922 is arguably the most famous Klee work of all time), before coming back to colourful, abstract, somewhat cubist works in the 1930s - of which Characters in Yellow is a great example.