A more thorough explanation:

AUXILIUM AD FILIUM MILITEM FACIENDUM ET FILIAM MARITANDAM

AUXILIUM AD FILIUM MILITEM FACIENDUM ET FILIAM MARITANDAM (awg-zil-ee-əm ad fil-ee-əm mil-ə-tem fay-shee-en-dəm et fil-ee-am mar-ə-tan-dəm), n.[Law Latin] Hist. A writ ordering a sheriff to levy a tax toward the knighting of a son and the marrying of a daughter of tenants in capite of the Crown.

AUXILIUM AD FILIUM MILITEM FACIENDUM ET FILIAM MARITANDAM is a legal term in Latin that refers to a writ that was used in the past to order a sheriff to collect a tax from tenants in capite of the Crown. The tax was collected to help the tenants pay for the knighting of their sons and the marriage of their daughters.

An example of AUXILIUM AD FILIUM MILITEM FACIENDUM ET FILIAM MARITANDAM would be a situation where a lord who held land directly from the Crown had a son who was of age to become a knight and a daughter who was of age to be married. The lord would then request the writ to be issued to the sheriff, who would then collect the tax from the tenants in capite of the Crown to help pay for the expenses of knighting the son and marrying the daughter.