"It inscribes in an eminently elaborated form of simultaneity the conception of the whole incorporated into an electronic brain, using the quasi-instantaneity of communications"
This is from Lefebvre's "Writings on Cities," right? He's talking about neo-capitalism, here. Unlike the aims of capitalism, which preceded it, neo-capitalism considers both consumption and the ways that decisions are made as data and knowledge, rather than the concerns of people themselves. Using this data, neo-capitalism acts like a programmer on an "electric brain," or computer which controls a society (certainly a figurative brain/computer, probably really consisting of the city centre/political juncture of society).
"Inscribes" is not a literal use of the word, but rather a figurative use that evokes the meaning of carving into something, in this case, the computer chip of the "electric brain." Neo-capitalism programs society by "superimpos[ing]... the center of consumption upon the center of decision making." Because neo-capitalism, in contrast to capitalism, deals with the facts and figures of data rather than "people and things," it considers all of society without losing any of it ("conception of the whole"), since when capitalism considers "people and things" some information is always lost, perhaps due to the private aims of people with power in a capitalist system.
The part about communications means that communications have compressed time and space so much that they're as good as instant. So, these almost-instant communications are what allow neo-capitalism to program the electronic brain of society.