All of their time and space are foggy slum.So blot their maps with slums as big as doom

explain these line pls?

The underprivileged children who live in these slums do not have a sense of time and space because everywhere they are hemmed in by their circumstances. Their time and space are like a foggy slum that blots out their maps with a future that cannot be any different from their present. They are doomed to live their lives in such squalor and penury, relegated to the margins of society. For them, there is nothing to look forward to, their future is enshrouded in the fog of misery.