Hello.
If I may expand:
The name "ecuyer" means literally "someone you pay with an 'ecu'", the French money in usage in medieval times. Therefore an "ecuyer" was some sort of employee, by today's standards.
In ancient French chivalry, a knight usually had an "ecuyer", who was his apprentice in knighthood. Hence the association of the name with horse riding.
You also find in official French medieval texts mention of the French king having "ecuyers echansons", who were not horse riders at all, but managers in charge of overseeing the food supply for the king's kitchens and tables. (I know this from someone who studied Medieval History at Université de Montréal.)
In my own family tree, the alternate spellings "Lescuyer" and "L'Escuyer" are also found.
I hope this helps. Sincerely,
Christian L'Écuyer
Gatineau (Qc), Canada