"algunas" is formed with "algun+a+s"
where the "a" is the feminine and the "s" is plural.
Algun means "some": algun pais: some country, algun amigo: some friend
so algunas means some for femininine plural: some parties.
party, Fiesta is feminine in spanish, so you need a feminine version of algun.
and the sentence means: some parties are celebrated in the house (casa not case!) of the family
well, in this context, fiesta can also be a "celebration" or "holiday", not only a party
so it means "some unspecified ones"
<span>Por favor, espere un momento, tengo que buscar mi cuaderno.
Please wait a minute, I have to get my notebook.
Hable más fuerte por favor.
Please speak louder.
Por favor, hable más despacio.
Please, speak slower.
Must not do.
Por favor, no grite en el teléfono.
Please, do not yell over the phone.</span><span>
No hable tan rápido, por favor.
Do not speak so fast please.
Source: Soy completamente bilingue y entiendo los dos lenguajes por igual/Speak fluent bilingual in both languages and understand both the same. Hope it helps/ Espero que le haya ayudado :)</span>