on the fourteenth day of this month, in the evening, according to all of its ceremonies and justifications.
Other versions
King James Version
In the fourteenth day of this month, at even, ye shall keep it in his appointed season: according to all the rites of it, and according to all the ceremonies thereof, shall ye keep it. English Standard Version
On the fourteenth day of this month, at twilight, you shall keep it at its appointed time; according to all its statutes and all its rules you shall keep it."New International Version
Celebrate it at the appointed time, at twilight on the fourteenth day of this month, in accordance with all its rules and regulations."