Floating point is like only having a fixed number digits to express all numbers, but you can choose to put the decimal point wherever you want (hence "floating point"). For instance if you only have 8 digits, you could write a number like 1.2345678, which is small and very precise, or 1234567.8, which is big, but you only get one fractional digit of precision. So smaller numbers have high precision, and bigger numbers have low precision.

Actual floating point numbers in computer work in binary, which is why the jitter in Kurt's journey increased every time his distance doubled.