if anyone cares for an actual explanation.
Yes, speedforce is basically a handwave/rule of cool/spiral power/deus ex.
"Speedforce is an sentient extra-dimensional power that comes from beyond the Source wall"
The Source wall in DC universe is the barrier that separates the dimensions/universes. Now, It needs to be noted, its not the same as the Bleed.
The Bleed is the area between universes, in cannon. The Source wall however is the OTHER direction. It is not a coincidence it sounds like the FOURTH wall. Until very recently, the barrier was not breached by any character. (white lantern Kyle did a few weeks ago, which is kindof bullshit. someone doesn't understand the entire point of the Source...) Speedsters have "gone into the speedforce" before. Dieing as characters, and entering the collected memories and conscious of the readers and authors.
so the speedforce exists as an authors ability to break the rules, and laws in universe. Particularly as "go fast" juice. But, in many other ways as well. out running death, the universe, himself, violating conservation of energy, friction, breaking anti-life, avoid time dilation, gravity, lets him actually see at speeds faster then light, etc.
Speedforce exists expressly as a meta-fiction.