Amines

There's a villain hiding in nomenclature. What is benzenamine? You probably imagined a phenyl group, a CH2 group and then NH2. No. What you imagined is phenylmethanamine. More correctly 1-phenylmethanamine. (Here, phenyl group becomes substituent as the side chain becomes the main chain) Benzenamine is nothing but aniline.

We'll begin with the basic character of amines, and I gotta say the table 13.3 in page 389 is utterly useless. It doesn't write things in the order of basic nature.
Here's the real thing.
From Most basic in aqueous phase
N-Ethylethanamine
N,N-Diethylethanamine
N-Methylmethanamine
Ethanamine
Methanamine
N,N-Dimethylmethanamine
Phenylmethanamine
Ammonia
N,N-Dimethylaniline
N-Methylaniline
Aniline (or Benzenamine)
To Least basic

Let's try to make sense.
Basic character, for amines, is due to that lone pair on N:
The more the electron density on the N, the more basic it must be, then.
-CH3 group is electron donating by +I
-C6H5 is electron withdrawing
So that explains why aromatic amines are less basic than ammonia, and aliphatic ones more basic.

But in water there's solvation effects to be taken care of. There's hydrogen bonding. The more the hydrogen bonding, the more stabilization of the positive charge on N (due to the loss of its electron pair). So when there's lesser substitution, there's more stability. (But ammonia can't still overtake substituted aliphatic amines. it's just the order among the substituted amines that we're talking about)
So, the disubstituted ones end up stronger, because they've two hydrogen bonds, and 2 -alkyl groups.
And now that order in page 391 makes sense. (It can be observed that roughly, inductive effect is stronger than solvation effect. That's why (C2H5)3-N is stronger than (C2H5)NH2. And in the second line, methyl groups don't have so much +I effect. So they follow the order of solvation effect.

Why aromatic ring takes away electron is pretty well known. There's resonance, there's this sp2 carbon. There're a lot of things.