Aho is an exclamatory word used in Jain prayers and stavan (devotional songs). It expresses surprise, praise, or deep emotion and is often repeated for emphasis, e.g., in verses that praise penance and virtue.

• In Jain devotional songs, “Aho! Aho!” is a natural way to voice admiration and devoted emotion toward the Tirthankaras, tapasvīs, or virtuous qualities.
• There isn’t a major difference in how “aho” is used between Digambar and Shwetambar traditions; it functions mainly as an expressive chant in prayers and bhajans.

You can see an example of its use in a Jain Knowledge piece here