PCIe 16 slot question

I would like to know what the difference is between x1 and x16?

This is from wikipedia regarding the PCIe16 slot:
PCI Express logo
Year created2003; 17 years ago
Created by
IntelDellHPIBM
Supersedes
AGPPCIPCI-X
Width in bits1 per lane (up to 16 lanes)
No. of devices1 on each endpoint of each connection.[a]
SpeedDual simplex (in each direction); examples in single-lane (x1) and 16-lane (x16):
Version 1.x: 2.5 GT/s
x1: 250 MB/s
x16: 4 GB/s