As you're learning more about image types, the difference between vector art and bitmap (or raster) art is essential. The laser really prefers vector art. Below are a couple of articles that may help you understand.

https://pediaa.com/what-is-the-difference-between-bitmap-and-vector/

https://www.lifewire.com/vector-and-bitmap-images-1701238

https://kb.iu.edu/d/afmr

File types like .SVG are one indication of vector art. But it's possible to load a bitmap into Inkscape and that doesn't actually convert it. You just have a bitmap image in an .SVG file.  

Much like pouring milk into a beer can doesn't make it beer.

Here's a couple of videos:

https://www.youtube.com/watch?v=fy9Pby0Gzsc

https://www.youtube.com/watch?v=fCw5lE_vbbc

Most 2D vector art packages can export an SVG or PDF file that the Lightburn software can accept. When cutting, always use the thinnest line width that your software supports. Be sure to use different colors for the areas you want to cut out versus to engrave (fill).

• Remember that the fill areas in your design will be engraved, large areas of black may take a long time to engrave
• When cutting, consider using more than one pass at a higher speed to minimize flare-up and charring your material.

Xerocraft recommends Inkscape for vector design work. It is free and open source.

You can also purchase Lightburn for your personal use. A free trial is also available.

Download Inkscape here

Download Lightburn here

Learning Inkscape:

Intro to Inkscape Video

Designing a CNC Project with Inkscape