You can find all of the following three words in a dictionary:
だから （だ + から）
であるから （である + から）
ですから （です + から)
だから = the "be" linking verb (a.k.a. "copula") + から
・だ, である and です are essentially just different forms of the same thing—the copula.
・から is a particle, in this case meaning "because" or "since".
Now... I can already hear people saying "Oi, hang on, sometimes だから comes right at the start of a sentence (like how it is used in strawhat's and Jinxu's examples). How can だ or です be the first word in a sentence!?"
How I think it works: What should have come before だ in the sentence is just something left unsaid and simply implied. What should have been said before だ would be literally just repeating the entire previous sentence again, or more likely referring to that previous sentence pronominally with それ ("that"). Taking Jinxu's example above:
I cannot drink milk. (それ)だから、I didn't drink it.
But basically all you need to know is that だから means is what the dictionary says—a conjunction meaning "so" or "therefore":
http://japaneseclass.jp/dictionary/%E3%81%A0%E3%81%8B%E3%82%89
[A]。だから、[B]。 = [A]. Therefore, [B].
[A]だから[B]。 = [B], because [A]. (Because [A], [B].)
July 6, 2016 at 9:20am
It means "that's why" or something along the lines.
I don't get it?
牛乳を飲めません。だから、飲まなかった。
You can find all of the following three words in a dictionary: