0.01 lot size in forex or micro lot is position size in trading. Position size of 0.01 lot for EURUSD currency pair, for every 10 pips gain will give a $1 profit (10 cents per pip). So for EURUSD means that 10 pips for 0.01 lot size profit is $1.
0.01 lot size or 1000 units or micro lot is the smallest position size when we talk about standard forex accounts.
The standard lot size forex is 1 lot and it is equal 100 000 units or $10 per each pip gain.
Below you can see Table of 3 types of position sizes:
Types of lot size:
Please see Figure below:
In video below is detail explanation: