Asking about the source of a quote is on topic on Literature Stack Exchange. See Is it on-topic to ask for help finding the source of a quote?. This category of questions is tagged with quote-source, which currently has the following tag wiki excerpt:

Questions seeking to identify the source of a quote. If possible, include the exact quote whose origin you're seeking, or describe it as closely as you can. (For questions seeking to identify a entire story or work of literature from some remembered details, use the [identification-request] tag instead.)

Asking about the meaning of a quote is on topic on Literature Stack Exchange if the quote is from a work of literature. (The distinction between questions asking to explain the meaning of a passage in a work of literature on the one hand and questions about the meaning of a quote from a literary work is not important.)

Since "literature" is impossible to define, you may get away with questions about the meaning of non-literary quotes, but that is not guaranteed. In addition, questions that can be answered by simple dictionary lookups may get migrated away or closed. However, the meaning of individual words and phrases in literary works often depends on context, and reading literature often means opening up meanings rather than finding "the one correct meaning" and this may be used as an argument against closing meaning questions. (We have What do we think about basic [meaning] questions? on our meta site, but this is really an ongoing discussion.)

Asking about the source of a quote is on topic on Literature Stack Exchange. See Is it on-topic to ask for help finding the source of a quote?. This category of questions is tagged with quote-source, which currently has the following tag wiki excerpt:

Questions seeking to identify the source of a quote. If possible, include the exact quote whose origin you're seeking, or describe it as closely as you can. (For questions seeking to identify a entire story or work of literature from some remembered details, use the [identification-request] tag instead.)

Asking about the meaning of a quote is on topic on Literature Stack Exchange if the quote is from a work of literature. (The distinction between, on the one hand, questions asking to explain the meaning of a passage in a work of literature and, on the other hand, questions about the meaning of a quote from a literary work is not important.) See the tag wiki excerpt for meaning:

Questions regarding the meaning of certain terms or phrases used in a work of literature. If your question concerns the symbolic significance of something whose surface meaning is clear, use the [symbolism] tag instead. (...)

Since "literature" is impossible to define, you may get away with questions about the meaning of non-literary quotes, but that is not guaranteed. In addition, questions that can be answered by simple dictionary lookups may get migrated away or closed. However, the meaning of individual words and phrases in literary works often depends on context, and reading literature often means opening up meanings rather than finding "the one correct meaning" and this may be used as an argument against closing meaning questions. We have What do we think about basic [meaning] questions? on our meta site, but this is really an ongoing discussion.