Answer

If you mean Beyashna / Biyāsan in Jain practice, it generally means taking food twice a day. In Jain panchang, it is also described as a vow taken after two prahars from sunrise. Since one prahar is one-fourth of the daytime, the exact clock time changes with local sunrise and sunset. ( jainfoundation.in)

Explanation

So there is no single fixed universal clock time for Beyashna. It depends on the day’s sunrise and sunset. In simpler Jain usage, it is understood as two meals in the day, usually keeping Jain food discipline in mind. ( jainfoundation.in)

Takeaway

If you are following the pachchakhān meaning, count two prahars after sunrise. If you mean the general practice, it simply means two meals a day. ( jainuniversity.org)