# first (array(N)) 
t = np.array([ 1., 4., -2., 7.])

creates an array of N elements. In this case 4 elements are filled.

try to print t[1] or t? what do you get? Note that indexing starts from zero.
first element t[0]
second element t[1]
third element t[2] 
Last element t[N-1]

You can also access all of the array element using a for-loop.

for i in range(N):