*Bhel- is a reconstructed Proto-Indo-European root word meaning, among other things, "bright," "burn," "shine," (which belong to *Bhel-1), "swell," (*Bhel-2) and "thrive," (*Bhel-3. Possibly.) not to be confused with the Hindi word Bhel (coward) or the food Bhelpuri.
*Bhel- is the source of a ridiculous number of modern words as it traveled through the etymological jungle to find its way into English, French, Old Norse, Old High German, Russian, and at some point it became the Ancient Greek "phlegein," (burn) earning itself a "fle/phle," noise, resulting in words like flame, flamboyant, and flamingo.
The *Bhel- bright came to mean white, and is the source of blanc/blanch. If you make something white, you bleach it. If you've got nothing but white, it's blank. Someone with bright hair is called blonde/blond. An empty place may be bleak.
*Bhel- burn gives us blaze, as well as the color of burned things, black. From there, a black spot marring a surface became a blemish. When you see nothing but blackness, or the sight you see after the brightest flash of light possible leaves you blind. If your face is burning, then you're blushing.
*Bhel- swell connected to full or rounded things, like ball, bloat, boulder. If your ego is swollen, you may be bold or bawdy. If something is thriving, it may be in bloom. That stuff that bursts out of you if you get cut is blood, and the thing that cut you is a blade.
I've focused in this WU on the B-sounding words *Bhel- is responsible for, but as the B-sound slowly transformed into a F/Ph sound, we also got words like affluent (your wealth swelling), flora (thriving plants) and one of the most amusing ones, phallus.