This may be a bit easier for you to read.

Metric Fasteners
Metric fasteners material, head style, and type are described in a similar manner to US fasteners. However, instead of threads per inch, the metric system uses thread pitch (the length of each thread in millimeters measured along the shaft of the bolt). The thread pitch is written between the diameter and length (both measured in millimeters) and is separated on each side by an X.
Typically the diameter of a metric bolt is preceded by a capital M to designate metric.

Example:
Class 8.8 Hex Bolt M10 x 1.5 x 20
This is a hex head bolt with a diameter of 10mm, a 1.5 thread pitch, measuring 20mm long and made of Class (grade) 8.8 steel.