The possible real name for this symbol could be Hrungnishjarta - or "Hungnir's heart" as it was mentioned in Snorri Sturlusson's Skáldskaparmál . Hrungnir, which in Old Norse meant 'brawler', is a jötunn in Norse mythology that dies by the hand of mighty Thor. According to myth, his heart was famous for being made of stone "with three sharp-pointed corners."

However the symbol likely predates even this story in Norse culture and we'll never actually know what the original name was. 

Today the term Valknut or valknútr comes from the term valknute - which is an ancient Norse symbol often seen on crafts, and maybe most notably the symbol for "command" on your Mac computer keyboard.  That symbol has another story altogether. But the term was basically lifted to project meaning on this three-part triangle design found in Norse imagery.

This modern neologism Valknut connects valr "the slain" and knut "knot." This largely because it's seen in carvings dealing with death ceremonies. But we don't really know if Vikings used the symbol in this way. They didn't exactly explain what the symbol meant even if it had a specific intent.

It's basically just cool, mysterious, and connected with Vikings! Here in Minnesota, we love everything Viking. We're very Norwegian, German, and Icelantic, so mysterious Norse icons and runes are often found on our tattoos, shirts, and decorations. We don't really know much about historical Viking symbols. And, to be honest, we don't really care.