random.seed and random.randn

[Truman]

import numpy as np 
np.random.seed(42)
x = np.random.randn(100)

I have a problem with understanding this simple code. Firstly, why 42 in parenthesis? Zero there would mean that the whole array is going to be remembered as it is. What's the difference with the other number inside?
regarding randn it gives standard normal distribution but I don't understand why does it give more numbers than 100. What 100 represents?

output:

Output:
[ 0.49671415 -0.1382643   0.64768854  1.52302986 -0.23415337 -0.23413696
  1.57921282  0.76743473 -0.46947439  0.54256004 -0.46341769 -0.46572975
  0.24196227 -1.91328024 -1.72491783 -0.56228753 -1.01283112  0.31424733
 -0.90802408 -1.4123037   1.46564877 -0.2257763   0.0675282  -1.42474819
 -0.54438272  0.11092259 -1.15099358  0.37569802 -0.60063869 -0.29169375
 -0.60170661  1.85227818 -0.01349722 -1.05771093  0.82254491 -1.22084365
  0.2088636  -1.95967012 -1.32818605  0.19686124  0.73846658  0.17136828
 -0.11564828 -0.3011037  -1.47852199 -0.71984421 -0.46063877  1.05712223
  0.34361829 -1.76304016  0.32408397 -0.38508228 -0.676922    0.61167629
  1.03099952  0.93128012 -0.83921752 -0.30921238  0.33126343  0.97554513
 -0.47917424 -0.18565898 -1.10633497 -1.19620662  0.81252582  1.35624003
 -0.07201012  1.0035329   0.36163603 -0.64511975  0.36139561  1.53803657
 -0.03582604  1.56464366 -2.6197451   0.8219025   0.08704707 -0.29900735
  0.09176078 -1.98756891 -0.21967189  0.35711257  1.47789404 -0.51827022
 -0.8084936  -0.50175704  0.91540212  0.32875111 -0.5297602   0.51326743
  0.09707755  0.96864499 -0.70205309 -0.32766215 -0.39210815 -1.46351495
  0.29612028  0.26105527  0.00511346 -0.23458713]