Say why — because

から after a whole statement means “because”. The reason comes first, then から, and what follows is what the reason explains: あぶないですから、ここで あそんでは いけません — because it is dangerous, you must not play here. The order is the reverse of English: reason before consequence.

The reason can stand alone as an answer to why: どうして いかないんですか — あめですから. Politely the reason ends in です or ます before から; with friends the plain form is enough: あぶないから. The same から after a clock time or a place is “from”: くじから, from nine — what stands before it decides.