Stopping by the woods on a snowy evening synthesis

The poem Stopping by the woods on a snowy evening by Robert frost is About the narrator (Most likely Robert Frost) Stopping by the woods on a snowy evening the main idea is literally in the title.
I think the theme of this poem is mysterious because in the last stanza Frost writes "These woods are lovely dark and deep but I have promises to keep and miles to go before I sleep and miles to go before I sleep" I find this specific stanza mysterious because it doesn't mention what promises there are to keep why the woods are dark and deep and why he has miles to go before he sleeps. One new or difficult word in this poem is queer although I know the meaning of it I do not hear it used many times. Some repeated words are in the last stanza where it says twice and miles to go before I sleep.
I think Robert Frost chose the words lovely dark and deep to make it seem kind of gloomy yet beautiful. The poet uses literary devices such as stanzas, rhyme, speaker, tone and line break to convey his  ideas. This poem reminds me of my country house up in wood stock when its night time in the winter because everything looks creepy and mysterious and deep and scary thats how I can relate to the poem because I can really envision being surrounded by dark woods. My question is what is in the woods and what promises does frost have to keep?