user15789: 
THe product: (https://www.sparkfun.com/products/12009)
So guys, here' s a pretty simple but important question for me:
Can I convert 3.7V (li-po battery's voltage level) to 5V's (I do have arduino pro mini running on 5 volts) using 3.3v to 5v converter (picture shown above...) ??
Thanks already...

user4143: No. That is a level shifter. It uses a low voltage (3.3V) to switch a separate high voltage (5V) supply to create different logic levels.
It does not convert voltage, it merely switches.
To create 5V from 3.7V you need either a boost converter (inductor based circuit) or a charge pump converter (capacitor based circuit). 

15789: <p><a href="https://i.stack.imgur.com/NL4YV.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NL4YV.jpg" alt="Bidirectional logic level converter"></a>
THe product: (<a href="https://www.sparkfun.com/products/12009" rel="nofollow noreferrer">https://www.sparkfun.com/products/12009</a>)</p>

<p>So guys, here' s a pretty simple but important question for me:
Can I convert 3.7V (li-po battery's voltage level) to 5V's (I do have arduino pro mini running on 5 volts) using 3.3v to 5v converter (picture shown above...) ??</p>

<p>Thanks already...</p>
 4143: <p>No. That is a level shifter. It uses a low voltage (3.3V) to switch a separate high voltage (5V) supply to create different logic levels.</p>

<p>It does not convert voltage, it merely switches.</p>

<p>To create 5V from 3.7V you need either a <em>boost converter</em> (inductor based circuit) or a <em>charge pump</em> converter (capacitor based circuit). </p>
