It is only contagious if there is direct contact since it is a bacterial infection. There are treatments like applying warm water which she can use to heal the area heal faster. She should avoid wearing any makeup during the period as well as contact lenses until she heals. You can get more information on this at http://www.webmd.com/eye-health/tc/styes-and-chalazia-topic-overview.
I had one and I worked with small kids so my dr told me to stay home a few days. He gave me some eye drops and told me to wet a wash cloth with warm water and lay it over my eyes (i had one on the right eye and the got it on my left a few days latter) for 15 min a few times a day.