In which part of the empty screen on desktop should text content be placed for most effective readability for user? Suppose that short info is all content (like on the picture below). People read (skim) from upper left to bottom right, so is it more useful to place text block in upper left corner?
Center it (horizontally and vertically)
If you are required to show the necessary information, you can wrap the whole section into a card or a div and utilize the remaining space like these big sites do.
You can even take the example of the login/signup page which is probably the first page that these sites show.
So yeah, in short, make the copy to lie in the center(horizontally and vertically) and you can use the bg to make it aesthetically pleasing.
If you only show this amount of data, you'll need to draw attention to it.
It's much easier to look straight forward, than to look either to the left or the right. You'll create focus for the content because it's surrounded by equal amounts of white space on each side. You'll also be able to adapt it to mobile with ease. You may want to align your text to the left though, if readability is at stake. With a right text alignment, your users have to make more effort into reading the lines because the labels are of different length.
Contained within the center, but left-align the text. I think the reading top-let to bottom-right applies to right-to-left readers, and it’s not always the case when not a block or page of text. A screen on a computer is more like a billboard and less like a book.
Center: Screen sizes can be as small as a watch face, up to huge. Most user mouse movements, in my experience, tend to be concentrated in the center of the screen. When looking at images (or screens), we tend to start in the center (or the corners) and then use the design to cue us into concentrating in other area. It’s also become a UX convention, particularly online (most alerts, news feeds, etc). Most users sit center to their monitor; so, center placement means they don’t have to turn their heads or eyes.
Contained: If you have black text on a white background isolation and contrast are being used to get the user to the text, you can apply (enhance) this to (by) wrapping the text in a container wherein the container to ground contrast is also high (“cards” so to speak).