basically a conversion turns something into something else
for example, you cant add an integer and a real together, eventhough they are both numbers...
so instead of going:
Trigger:
Actions
Set Real[1] = Real[1] + Integer
you do this
Trigger:
Actions
Set Real[1] = Real[1] + Real(Integer)
which converts the integer variable into a real number, real numbers are capable of having decimals (ie: 1.50, 3.21), integers arent (ie: 1, 2, 3)
with conversions you can turn an integer into a real, or string, etc and visa-versa (reals with decimals changed into integers just take off the decimal (ie: 1.99 - > 1)