I don't understand what this regular language is asking for? Find a grammar for L(G) = {w || w | is odd,∑ = (0, 1) }
Yup, I can see why that would be confusing.  The typesetting is probably making this harder to follow.  I'm guessing what's written is $\{w \mid |w| \text{ is odd}, \ldots\}$.   This is the set of all $w$ such that $|w|$ is odd etc.  Here $|w|$ typically represents the length of the word $w$.

It might have been clearer if the author had used a colon instead of a vertical line in our set builder notation: then it would have been written $\{w : |w| \text{ is odd}, \ldots\}$, and maybe it would be easier to see what is going on..