Via
noun, する verb
You pass through somewhere for a reason, so you're going via that place.
けいゆ
This is a jukugo word that uses the on'yomi readings of the kanji. You learned this reading for 経 with the kanji, and you learned this reading for 由 with the word 由来. If you need an extra reminder for that one, here's a mnemonic just in case:
If you're going via an unfamiliar place, I recommend you seek out a yurt (ゆ) to stay in. Wherever it is you're going via, you can't go wrong if you stay in a yurt.
京都に東京経由で行った時です。
That's the time I went to Kyoto via Tokyo.
大阪を経由しても行けますよ。
You can also go via Osaka.
旅館の予約は、インターネット経由で行うのが一番いいと思う。
I think it's best to book your inn via the internet.