First you need the basics to understand the metric system. 

The metric system is based on a decimal system (ie:powers of ten). Therefore, it simplifies calculations by using a set of prefixes shown in the table below.

Multiplication Factor Prefix Symbol U.S Name
1,000,000,000 = 10 9 giga G billion
1,000,000 = 10 6 mega M million
1,000 = 10 3 kilo k thousand
100 = 10 2 hecto h hundred
10 = 10 1 deca da ten
1 = 1     one
0.1 - 10 -1 deci d tenth
0.01 = 10 -2 centi c hundredth
0.001 = 10 -3 mili m thousandth
0.000001 = 10 -6 micro µ millionth
0.000000001 = 10 -9 nano n billionth

Symbols must be written exactly as shown in the tables. Do not change the case, or add an "s" for the plural, or use abbreviations, or write a period after a symbol (unless it ends a sentence).

The symbols (not abbreviations) for SI units are the same all over the world, regardless of the local language spoken.