I’m slightly confused by “einiges”…“einige” usually seems to mean “a few” or “some”, i.e. not very many of something. But then “einiges” often seems to mean “quite a lot”. Is it a different word or a form of the same word?
It must be because of declination but I am too much of a grammar noob to explain how.
Spiega un sacco.This is not the correct translation: einiges is *few things" the exact opposite of un sacco that is a lot in english. So the correct translation in italian is Questo spiega alcune cose
In this special case “einiges” means indeed “a lot”. So “un sacco” is an adequate translation.
I think also the degree of colloquialism is comparable. It is nothing that you would write.
You are right. It can be even written. einiges is in the middle between nothing and a lot
"Das erklärt einiges"sometimes also “Das erklärt so einiges” is a fixed expression.
An example for usage:
“Thomas war doch immer ein guter Student. Warum hat er die letzte Klausur vergeigt?”
“Er hat gerade Probleme mit seiner Freundin.”
“Das erklärt (so) einiges.”
"Thomas has always been good student, hasn’t he? Why has he botched the last (written) exam?
“Just now he has some problems with his girlfriend.”
“That explains it./That explains a lot.” or “Spiega un sacco.”