休(やす)みの日(ひ)は家(いえ)で本(ほん)を読(よ)みます。

This phrase describes a typical activity during leisure time. "休みの日" (yasumi no hi) refers to "days off" or "holidays." "家で" (ie de) indicates the location of the action, "at home," while "本を読みます" (hon o yomimasu) means "read books."

休日(きゅうじつ)によくする活動(かつどう)について話(はな)す時(とき)に使(つか)います。「〜で」は行動(こうどう)の場所(ばしょ)を示(しめ)す助詞(じょし)です。