"Lightght" is the name of the poem, and it's the full poem itself. The doubled voiceless "gh" evokes the bright and instant quality of light itself, though critics of all that is postmodern were displeased:
One of Saroyan's most famous poems was simply the unconventionally spelled word "lighght" in the center of a blank page. This poem was selected by George Plimpton to be featured in The American Literary Anthology and, like all poems in the volume, received a $750 cash award from the National Endowment for the Arts, then just 20 years old. The NEA was created in the same year the poem was written, 1965. Many conservatives, such as Representative William Scherle and Senator Jesse Helms, objected at the per-word amount of the award, complaining that the word was not a real poem and was not even spelled correctly. This was the NEA's first major controversy; 25 years after it was written "Ronald Reagan was still making pejorative allusions to 'lighght.'" Grumman says the poem is "neither trivial nor obscure", but plays with the glimmering quality of light, leaving us with "intimations of his single syllable of light's expanding, silently and weightlessly, 'gh' by 'gh', into...Final Illumination." Saroyan himself explains that "the difference between "lighght" and another type of poem with more words is that it doesn't have a reading process"; it is a poem you "see rather than read".
And what a nice description: a poem you see rather than read. Instant, immediate, beyond thought. It is more like a Rothko than a Rembrandt.