to be (classical)
也 is a classical grammatical character that functions as a copula, meaning "to be" or "is," often used at the end of sentences in classical Chinese and Japanese texts.
也 is an ancient character whose original pictographic meaning is uncertain. It was borrowed early as a grammatical particle meaning "to be" or marking a pause, and its modern form is a stylized simplification of an older shape.
The simple, balanced strokes of 也 look like a classical seal or stamp, marking a statement as definitive: "it is."
For ヤ, imagine a classical scholar nodding and saying "yah" (like a casual "yes") to confirm a statement: yah -> ヤ, and 也 means "it is."