For black and white film only: You will only care about even and strong light, everything else we say about light 'quality' and CRI and color is unimportant if you only scan BW.
Scanning color is a bit more complex, and different light sources have different build-ups of wavelengths. Essentially a bad light source can have a big ‘gap’ in a colour, so that, for example, the blue in your image is rendered very dull, if as blue at all, and not some other color.
You will see a lot of talk about 'CRI' - this stands for Color Rendering Index, and is an attempt at making a scale that represents the accuracy of a light. Click here to read more about color rendering. CRI above 90 is good, anything below is unsuited for color scanning.
You want a bright light to give your scan a short shutter speed to minimize vibrations
For color scanning you want a CRI above 90
Your light has to evenly light up the film area
The light needs to sit flat on the table