在る
ある · aru · JLPT N5 · verb-godan
to be
aru: ARE you there? Then you exist — and what exists near you, you have
ある sounds like English are, the verb of being. Japanese says having as existing: a book exists to me = I have a book. So one verb covers both to be and to have. It is used for non-living things; living ones take いる.
在 — earth 土 + phonetic 才
Originally a phono-semantic compound: 土 (earth) gives the meaning of a place or location, while 才 supplies the sound. It came to mean 'to be present/located at,' and now also serves as a grammatical marker for ongoing actions, like 'in the middle of doing.'